2. Introduction
• This presentation will cover (at the 50,000 foot level) many different
areas (but not all) of z/OS
• Don’t be overwhelmed. There is a ton of material here. The purpose
of this session is to acquaint you with some of the major concepts of
z/OS
z/OS Concepts #CC 2
3. Agenda
Why Z Matters and Why z/OS
Hardware/LPAR
z/OS Components
Software Stack
App Dev, App Exec and Mgmt Envs
DASD
Data Sets / Allocation
PDS & PDSE
VTOC & Catalogs
SMS
TSO/E
ISPF
z/OS UNIX/ISHELL/OMVS/Remote
Address Spaces & Modes
Storage & DAT
Batch Processing/JES/JCL
SDSF
Job Flow
System Log
IPL
Sysplex/GDPS
Serialization
Managing Workloads
z/OS Concepts #CC 3
5. Why Z Matters
z/OS Concepts #CC 5
Utilities Retail
Government Financial
Travel
Healthcare
Automotive
Telecoms
Weather
6. Why Z Matters
Mainframes process 30 billion
business transactions per day
z/OS Concepts #CC 15
Mainframes process 1.3 million
CICS transactions. Every second. Every day.
Mainframes enable $6 trillion
in card payments annually
80 percent of the world’s corporate
data originates on mainframes
91 percent of CIOs said new customer-
facing apps are accessing the mainframe
7. Why z/OS?
z/OS Concepts #CC 16
• Ideally suited for processing large workloads for many concurrent users
• Highest security ratings for an OS
• Highest reliability
• Low TCO compared to other enterprise competitors
• Designed for:
• Serving 1000s of users concurrently
• I/O and numeric intensive computing
• Processing very large heterogeneous workloads
• Running mission critical applications securely
9. z/OS Lineage
• At the beginning there was:
• OS/360 (1966)
• Configuration options PCP, MFT and MVT
• OS/VS2 R1 (~1972)
• Retroactively renamed to SVS
• OS/VS2 R2 (~1974)
• Also called MVS
• MVS/370 (~1977)
• MVS/SP V1
• Optionally DFDS and DFEF
• MVS/XA (1983)
• MVS/SP V2 or V3 and MVS/DFP
• MVS/ESA (~1990)
• MVS/SP V4 or V5
• Either MVS/DFP or DFSMS/MVS
• OS/390 (1996)
• z/OS (2001)
z/OS Concepts #CC 18
Since 2001 the name
has remained z/OS
This is the longest
that it has been called
one name!
Since 2001 the name
has remained z/OS
12. IBM Z Server – Multiple LPARs
z/OS Concepts #CC 21
CP, Memory, I/O
PR/SM™
LPAR
LPAR
LPAR
LPAR
LPAR
LPAR
LPAR
Support Element (SE)
Up to 85
LPARs can be
defined
Each LPAR can
be allocated
different
amounts of
resources (up to
16TB memory)
13. IBM Z Hardware and z/OS
z/OS Concepts #CC 22
Support Element (SE)
CP, Memory, I/O
PR/SM™
z/OS®
ICF
–
CFCC
z/VSE®
z/TPF
z/VM®
z/OS®
Linux
on
z
Systems®
Linux
on
z
Systems®
Linux
on
z
Systems®
Linux
on
z
Systems®
z/OS (a.k.a. Multiple Virtual
Storage - MVS)
Where we will be spending our
time
15. z/OS Concepts – Elements, Features,
Components
• z/OS is a collection of elements
• Each element consists of a collection of modules (called components)
z/OS Concepts #CC 24
Examples:
IOS, RSM, GRS, Contents,
Allocation, Consoles, NIP,
Scheduler, SMF, BCPii, Logger
16. z/OS Concepts – Elements, Features,
Components
• z/OS is a collection of elements
• Each element consists of a collection of modules (called components)
• Base elements are always included in z/OS
• BCP (Base Control Program)
• DFSMSdfp (Data Facility Storage Management Subsystem)
• Deliver essential operating system functions
z/OS Concepts #CC 25
Other Base Elements:
Communication Server, z/OSMF,
HLASM, TSO, ISPF, JES2,
Metal C Runtime Library
17. z/OS Concepts – Elements, Features,
Components
• z/OS is a collection of elements
• Each element consists of a collection of modules (called components)
• Base elements are always included in z/OS
• BCP (Base Control Program)
• DFSMSdfp (Data Facility Storage Management Subsystem)
• Deliver essential operating system functions
• Optional features installed in addition to base elements
• Requested separately from base elements
• Can be priced or free
z/OS Concepts #CC 26
Optional Features
Examples:
Security Server, SDSF,
XL C/C++, RMF, JES3,
DFSMShsm, DFSMSdss
19. IBM z/OS Software Stack
z/OS Concepts #CC 28
z/OS®
Operating System
Middleware
Applications
Provides critical set of
system services made
possible by the
z/Architecture® and
firmware
20. IBM z/OS Software Stack
z/OS Concepts #CC 29
z/OS®
Operating System
Middleware
Applications
Software that is
neither operating
system code nor an
end-user application
21. IBM z/OS Software Stack
z/OS Concepts #CC 30
SAP is the registered trademark of SAP SE in Germany and in several other countries.
z/OS®
Operating System
Middleware
Applications
Db2® Data Base 2
CICS® Customer Information Control System
IMS™ Information Management System
WAS WebSphere® Application Server
IBM MQ IBM Message Queuing
SAP® Systems, Applications and Products in Data
Processing
TSO/E Time Sharing Option/Extensions
22. IBM z/OS Software Stack
z/OS Concepts #CC 31
z/OS®
Operating System
Middleware
Applications Provide end-user
interface to product
solutions
ISPF Interactive System Productivity Facility
SA z/OS IBM System Automation for z/OS
24. Application Development Env
z/OS Concepts #CC 33
z/OS supports many programming languages as well as
modern IDEs and environments
25. Application Development Env
z/OS Concepts #CC 34
z/OS supports many programming languages as well as modern
IDEs and environments
• Assembler
• COBOL
• C/C++
• PL/I
• Fortran
• REXX
• JAVATM
• Python
• Node.js
• Scala
28. Application Development Env
z/OS Concepts #CC 37
Legacy interactive interface
Integrated Development
Environment (IDE)
Other Modern Application
Development Tools
36. IBM Speak – Data Set
• Data set
• Think “File”
• Contains data in different structured formats
• Need to choose the format of data set and reserve
space (allocate dataset) prior to using for the first time
• Resides on DASD, Tape
• z/OS has types of data sets
• Legacy Data set
• Unix file
z/OS Concepts #CC 45
IBM prefers the
spelling “data set” to
“dataset”
37. IBM Speak – Data Set
z/OS Concepts #CC 46
DSORG=PS (Physically Sequential)
Data
Editing the data set gives you all
the data in the data set
38. Directory
IBM Speak – Data Set
z/OS Concepts #CC 47
DSORG=PO (Partitioned)
DSORG=PS (Physically Sequential)
Data
Member 2 Data
Member 1 Data Member 3 Data
The PDS contains a directory to
locate the members
39. PDS & PDSE
• PDSE data sets can be used in place of nearly all PDS data sets
• PDSE designed to address running out of space issues
• Compression is not necessary
• PDSE directory expands to fit the members
z/OS Concepts #CC 48
40. IBM Speak – Data Set Name
• Data set name (DSN or DSName)
• Think “File Name”
z/OS Concepts #CC 49
41. IBM Speak – Data Set Name
• Data set name (DSN or DSName)
• Think “File Name”
• 1 to 22 segments
• segments separated by a period
• each segment limited to 8 characters
z/OS Concepts #CC 50
FRED.ASSEMBLE.SOURCE
42. IBM Speak – Data Set Name
• Data set name (DSN or DSName)
• Think “File Name”
• 1 to 22 segments
• segments separated by a period
• each segment limited to 8 characters
• Up to 44 characters (includes periods)
• High-level qualifier (HLQ) is typically your userid
z/OS Concepts #CC 51
FRED.ASSEMBLE.SOURCE
High-level
qualifier
(HLQ)
Low-level
qualifier
44. IBM Speak – Data Set Allocation
• Data set allocation
• Think “Create Space” for a data set on disk
z/OS Concepts #CC 53
45. IBM Speak – Data Set Allocation
• Data set allocation
• Think “Create Space” for a data set on disk
• Need:
• Data set name
• VOLSER (i.e., the DASD volume) where the space should be
allocated
• Data set attributes (Size, RECFM, LRECL, BLKSZE, DSORG)
z/OS Concepts #CC 54
47. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 56
VOL100
FRED.ASSEMBLE.SOURCE
Allocate space for data set
FRED.ASSEMBLE.SOURCE
on volume VOL100
VOLSER
48. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 57
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
DASD volume has a Volume
Table of Contents (VTOC) that
locates a data set on the
volume
49. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 58
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
VOL002
SYS1.USERCAT
FRED.ASSEMBLE.SOURCE
is on VOL100
To simplify find the data set,
the name and location
information is placed in a
catalog
50. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 59
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
VOL002
SYS1.USERCAT
FRED.ASSEMBLE.SOURCE
is on VOL100
There can be many catalogs
so how do we locate the
correct one?
51. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 60
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
VOL001
SYS1.MSTRCAT
FRED.* data sets
cataloged in
SYS1.USERCAT on VOL002
VOL002
SYS1.USERCAT
FRED.ASSEMBLE.SOURCE
is on VOL100
We look in the “Master”
catalog (of which there is
only one)
52. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 61
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
VOL001
SYS1.MSTRCAT
FRED.* data sets
cataloged in
SYS1.USERCAT on VOL002
VOL002
SYS1.USERCAT
FRED.ASSEMBLE.SOURCE
is on VOL100
The master catalog contains an HLQ of
FRED and indicates that all of Fred’s
data sets are cataloged in the user
catalog named SYS1.USERCAT
53. IBM Speak – VTOC & Catalogs
z/OS Concepts #CC 62
VOL100
FRED.ASSEMBLE.SOURCE
VTOC
VOL001
SYS1.MSTRCAT
FRED.* data sets
cataloged in
SYS1.USERCAT on VOL002
VOL002
SYS1.USERCAT
FRED.ASSEMBLE.SOURCE
is on VOL100
Now we can tell z/OS to find
FRED.ASSEMBLE.SOURCE without
giving any more location information
55. z/OS Concepts – SMS
• Data set management is tedious & error prone
z/OS Concepts #CC 64
56. z/OS Concepts – SMS
• Data set management is tedious & error prone
• IBM introduced SMS (System-Managed-Storage) to address this concern
z/OS Concepts #CC 65
60. Interacting with z/OS – TSO
• End users (sometimes tens of thousands of them) use the
system
• TSO/E (Time Sharing Option/Extensions) allows users to log on and
interactively share resources
• Supports limited set of basic commands
• Sometimes called using TSO in its “native mode”
z/OS Concepts #CC 69
61. Interacting with z/OS – TSO
• End users (sometimes tens of thousands of them) use the
system
• TSO/E (Time Sharing Option/Extensions) allows users to log on and
interactively share resources
• Supports limited set of basic commands
• Sometimes called using TSO in its “native mode”
z/OS Concepts #CC 70
62. Interacting with z/OS – TSO
z/OS Concepts #CC 71
You provide your userid
and password
63. Interacting with z/OS – ISPF
z/OS Concepts #CC 72
Because TSO/E
native mode
supports limited
functions, most
users go right to ISPF
65. Interacting with z/OS – ISPF
• ISPF (Interactive System Productivity Facility)
• Full panel application
• Panels are hierarchical
z/OS Concepts #CC 74
66. Interacting with z/OS – ISPF
• ISPF (Interactive System Productivity Facility)
• Full panel application
• Panels are hierarchical
• Navigated via keyboard
• F7 and F8 scroll backward and forward
• Enter (not right-ctrl) moves cursor to next input field
• Home moves cursor to first input field
• ISPF use of Function Keys
• Provides text editor and browser
• Data set utilities
• Allocation
• Deletion
• Locating and Listing
• etc.
z/OS Concepts #CC 75
67. Interacting with z/OS – ISPF
z/OS Concepts #CC 76
Specify the data set
name (or use wildcards)
that you want to display
and press Enter
68. Interacting with z/OS – ISPF
z/OS Concepts #CC 77
Side note:
To list the available
commands, enter a
slash “ / “
69. Interacting with z/OS – ISPF
z/OS Concepts #CC 78
Enter the number
of the function you
desire
72. Interacting with z/OS – UNIX
• z/OS UNIX a certified UNIX operating system by the Open Software
Foundation
• z/OS UNIX® provides another interactive way to access z/OS
• UNIX-compliant applications can be recompiled on z/OS unmodified and run
directly on z/OS
• Before we examine some UNIX functions, we need to understand the
z/OS UNIX file system
• In particular, the zFS (zSeries File System)
z/OS Concepts #CC 81
UNIX is a registered trademark of The Open Group
73. Interacting with z/OS – UNIX zFS
• Path name identifies a file
• Consists of directory names and a file name
• Up to 1023 characters
• Directories and file name separated by a forward-slash ( / )
/dir1/dir2/dir3/MyFile
z/OS Concepts #CC 82
74. Interacting with z/OS – UNIX zFS
• Path name identifies a file
• Consists of directory names and a file name
• Up to 1023 characters
• Directories and file name separated by a forward-slash ( / )
/dir1/dir2/dir3/MyFile
• Names are case sensitive
z/OS Concepts #CC 83
75. Interacting with z/OS – UNIX
• z/OS UNIX provides three main environments
• ISHELL & z/OS UNIX Directory List Utility
• ISPF panel interfaces to z/OS UNIX System Services
• Good for users familiar with TSO and ISPF
z/OS Concepts #CC 85
76. Interacting with z/OS – UNIX
• z/OS UNIX provides three main environments
• ISHELL & z/OS UNIX Directory List Utility
• ISPF panel interfaces to z/OS UNIX System Services
• Good for users familiar with TSO and ISPF
• OMVS
• The z/OS UNIX shell
• Users of current UNIX systems find the z/OS UNIX shell environment familiar
z/OS Concepts #CC 86
77. Interacting with z/OS – UNIX
• z/OS UNIX provides three main environments
• ISHELL & z/OS UNIX Directory List Utility
• ISPF panel interfaces to z/OS UNIX System Services
• Good for users familiar with TSO and ISPF
• OMVS
• The z/OS UNIX shell
• Users of current UNIX systems find the z/OS UNIX shell environment familiar
• Remote UNIX interfaces
• z/OS UNIX can be accessed thru standard UNIX interfaces remotely
• Telnet, SSH, NFS
z/OS Concepts #CC 87
88. Interacting with z/OS - Telnet
z/OS Concepts #CC 98
• Remote command execution
• Connection may be encrypted
• Automatically converts EBCDIC on the mainframe side to ASCII on the
user side
• Telnet client is needed
• Userid/password of valid z/OS userid required
89. Interacting with z/OS – SSH
z/OS Concepts #CC 99
• Remote command execution
• Connection is encrypted
• Automatically converts EBCDIC on the mainframe side to ASCII on the
user side
• SSH client is needed
• Public/private encryption key pair needs to be generated
• No userid/password needs to be specified
• Public key needs to be stored on z/OS
91. Interacting with z/OS – NFS
z/OS Concepts #CC 101
• Network file system
• Acts as a file server to remote systems
• Client sees data sets or files as if they are local resources
• Access to both traditional z/OS data sets and z/OS UNIX files
• Connection may be encrypted
• Automatically converts EBCDIC on the mainframe side to ASCII on the
user side
• NFS client is needed
• mvslogin command required to logon to z/OS
• mount command used to make a connection between a drive letter of
local system and z/OS data sets or z/OS UNIX directories
92. Interacting with z/OS – NFS
z/OS Concepts #CC 102
c:znfs-client-utils>mvslogin mvshost smith
GFSA968I UNIX uid=502/gid=1000 for user JSmith obtained
from local passwd file.
Password required
GFSA973A Enter MVS password for SMITH: ********
GFSA955I SMITH logged in ok.
c:znfs-client-utils>mount mvshostmvssmith J:
J: is now successfully connected to mvshostmvssmith
The command completed successfully.
c:znfs-client-utils> J:
j:>
94. z/OS Address Spaces
z/OS Concepts #CC 104
z/OS®
z/OS is structured around address spaces
Address spaces are ranges of addresses in
virtual storage
Each user gets an address space containing
the same range of addresses
95. z/OS Address Spaces
z/OS Concepts #CC 105
z/OS®
z/OS is structured around address spaces
Address spaces are ranges of addresses in
virtual storage
Each user gets an address space containing
the same range of addresses
96. z/OS Address Spaces
z/OS Concepts #CC 106
z/OS®
z/OS is structured around address spaces
Address spaces are ranges of addresses in
virtual storage
Each user gets an address space containing
the same range of addresses
97. z/OS Address Spaces
z/OS Concepts #CC 107
Wilma
0
16 MB
2 GB
16 EB
Barney
Fred
Each user’s
address space has
the same range of
addresses
0 – 16 EB
(exabyte)
1 EB = 1 billion
gigabytes (1018)
98. z/OS Address Spaces
z/OS Concepts #CC 108
PCAuth
RASP
Master
Besides an
address space for
each user, z/OS
creates address
spaces (~35) for
some of its
internal
components
Trace
DumpSrv
XCFAS
GRS
99. z/OS Address Spaces
z/OS Concepts #CC 109
SDSFAUX
VTAM
SDSF
TCAS
TCPIP
XCFAS
GRS
PCAuth
RASP
Master
Trace
DumpSrv
Then address
spaces for
middleware
and
applications
are created
101. What Makes Up an Address Space?
z/OS Concepts #CC 112
Prefixed Save Area (PSA)
System code and data
common to all address spaces
z/OS system data for the address space
Not available to z/OS. Used by JAVA™
Shared and common data areas
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
z/OS has storage ranges that
contain code/data that is
common to all address spaces
102. What Makes Up an Address Space?
z/OS Concepts #CC 113
Prefixed Save Area (PSA)
System code and data
common to all address spaces
z/OS system data for the address space
Not available to z/OS. Used by JAVA™
Shared and common data areas
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
Private Area
Private Area
Private Area
Private Area
What is left is
the “Private
Area” that is
available for
your use
103. What Makes Up an Address Space?
z/OS Concepts #CC 114
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
But how much
can your
program see
(i.e., address)?
105. Addressing Modes
z/OS Concepts #CC 116
16 MB
0
An address space size
is limited to the
amount of memory
that can be addressed
In 1977, an address
space was limited to
16 MB
108. Addressing Modes
z/OS Concepts #CC 119
2 GB
16 MB
“The
Line”
0
MyPgm24
Programs not changed to
support 31-bit addressing
had to run and could only
access data that was
“Below the line”
Data
109. Addressing Modes
z/OS Concepts #CC 120
2 GB
16 MB
“The
Line”
0
MyPgm24
MyPgm31
Programs changed to
support 31-bit addressing
could run and could also
access data that was
“Above the line”
Data
Data
110. Addressing Modes
z/OS Concepts #CC 121
2 GB
16 MB
“The
Line”
0
MyPgm24
MyPgm31
Needed a way to indicate
which addressing mode the
program supported
Programs now have to
specify:
AMODE 24 or
AMODE 31
Data
Data
111. Addressing Modes
z/OS Concepts #CC 122
2 GB
16 MB
“The
Line”
0
MyPgm24
MyPgm31
Since AMODE 31 programs
could run (i.e., be loaded)
above or below the line, a
way was needed to request
where the program should
reside
Data
Data
112. Addressing Modes
z/OS Concepts #CC 123
2 GB
16 MB
“The
Line”
0
MyPgm24
MyPgm31
Programs now have to
specify a residency mode:
RMODE 24 or
RMODE 31
so z/OS knows where to
load the program
Data
Data
113. Addressing Modes
z/OS Concepts #CC 124
2 GB
16 MB
“The
Line”
0
MyPgm24
MyPgm31
AMODE 31
RMODE 31
Data
Data
AMODE 24
RMODE 24
114. Addressing Modes
z/OS Concepts #CC 125
2 GB
16 MB
“The
Line”
0
MyPgm31
Data
Data
AMODE 31
RMODE 24
This request is
also possible
115. Addressing Modes
z/OS Concepts #CC 126
2 GB
16 MB
“The
Line”
0
Data AMODE 24
RMODE 31
This request is impossible!
Branches within MyPgm24 would
fail since the target location is in 31-
bit storage but the address being
used is a 24-bit address
MyPgm24
116. Addressing Modes
z/OS Concepts #CC 127
~
~
~
~
16 MB
“The
Line”
16 EB
0
In 2000, an address
space size in creased
to 64-bit or
16 EB
117. Addressing Modes
z/OS Concepts #CC 128
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
The concept of
“The Bar” was
introduced
118. Addressing Modes
z/OS Concepts #CC 129
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
AMODE 64 is introduced
and data can now be
accessed “Above the
Bar”
While RMODE 64 is
supported by
z/Architecture, z/OS does
not support it
MyPgm6424
MyPgm6431
Data
Data
Data
119. Addressing Modes
z/OS Concepts #CC 130
~
~
~
~
2 GB
"The
Bar"
16 MB
“The
Line”
16 EB
0
MyPgm6424
MyPgm6431
Data
Data
With z/OS V2R3 and
beyond, z/OS supports
RMODE 64
With restrictions
Programs will be loaded
“Above the Bar”
MyPgm6464
Data
121. Storage
• Programs are written to utilize a given amount of memory.
z/OS Concepts #CC 132
122. Storage
• Programs are written to utilize a given amount of memory.
• The amount of memory required by all the running tasks is usually
much greater than the amount of real storage available.
z/OS Concepts #CC 133
123. Storage
• Programs are written to utilize a given amount of memory.
• The amount of memory required by all the running tasks is usually
much greater than the amount of real storage available.
• This is facilitated by the use of virtual storage.
z/OS Concepts #CC 134
125. Storage
z/OS Concepts #CC 136
The rest can stay in auxiliary
storage, enabling the remaining
real storage to be used for other
programs.
126. Storage
• Virtual storage is divided into 4KB pieces called pages.
• Real storage is divided into 4KB pieces called frames.
• Auxiliary storage is divided into 4KB pieces called slots.
z/OS Concepts #CC 137
128. Address Translation
• When a program is running, the processor must be able to
locate its virtual pages in real storage.
z/OS Concepts #CC 139
129. Address Translation
• When a program is running, the processor must be able to
locate its virtual pages in real storage.
• Address translation is the process that enables a processor
to convert virtual addresses into real addresses.
z/OS Concepts #CC 140
131. Batch Processing
• z/OS is also ideal for batch jobs
• Workloads that run in background
• Little or no human interaction
z/OS Concepts #CC 142
132. Batch Processing
• Many customer core applications, such as payroll, are performed
through batch processing (jobs)
• Jobs run without end user interaction
• Run as resources permit
• JCL (Job Control Language) is used to control the operation of each
job
z/OS Concepts #CC 143
135. Batch Processing
• An initiator (system program)
• Processes JCL
• Creates environment in an address space
• Runs the job in that address space
z/OS Concepts #CC 146
136. Batch Processing
• Management of jobs & resources are shared between z/OS and JES
(Job Entry Subsystem)
z/OS Concepts #CC 147
137. Batch Processing
• Management of jobs & resources shared between z/OS and JES
(Job Entry Subsystem)
• JES
• Receives jobs into system
• Queue jobs waiting to be executed
• Manages priority
• Schedules for processing
• Controls output processing
z/OS Concepts #CC 148
146. z/OS Concepts – SYSLOG
• What is the System Log?
• Better known as SYSLOG
• a.k.a. Hardcopy Log (at one time this was a printer)
• Chronological listing of messages about z/OS system activity and other major
middleware software products
• Issued system commands and their responses
• When an unexpected system problem occurs, the SYSLOG is the first
place to look to gather information about the problem
z/OS Concepts #CC 157
147. z/OS Concepts – SYSLOG
z/OS Concepts #CC 158
Message ID of a message
Every message starts with an ID
(up to 10 characters)
Enables you to look up message in
documentation
149. IBM Speak - IPL
• IPL – Initial Program Load
• Think “Boot the System”
• Starting z/OS
z/OS Concepts #CC 160
150. IBM Speak - IPL
z/OS Concepts #CC 161
Use a special console
connected to the internal
network of mainframe boxes
(HMC) and
activate the “Load Profile”
Profile contains DASD
device number to IPL
152. IBM Speak - IPL
z/OS Concepts #CC 163
Load Profile
Device address
to IPL
0980
0CE3W1
153. IBM Speak - IPL
z/OS Concepts #CC 164
IPL processed in
phases
Each phase
builds on the
previous
154. IBM Speak - IPL
z/OS Concepts #CC 165
0980
SYSRS1
To “Boot” or “IPL”
z/OS, the device
number of the
SYSRES (system
residence volume)
is specified
155. IBM Speak - IPL
z/OS Concepts #CC 166
JES2
RACF
RESOLVER
LLA
VLF
HZR
JES2AUX
MSI – several z/OS
component address
spaces created
After MSI, queued
START commands are
processed
Additional z/OS
component address
spaces are created
156. IBM Speak - IPL
Important address spaces started at Master Scheduler Initialization
time (MSI):
• SMF (System Management Facility)
z/OS Concepts #CC 167
Collector of system and job-
related information used for:
billing users, reporting reliability,
analyzing the configuration,
evaluating activity, profiling system
resource use, maintaining system
security.
157. IBM Speak - IPL
Important address spaces started at Master Scheduler Initialization
time (MSI):
• SMF (System Management Facility)
• System Logger
z/OS Concepts #CC 168
A set of services that allow an
application to write, browse, and
delete log data. Designed to
merge data from multiple
instances of an application,
including merging data from
different systems across a sysplex.
158. IBM Speak - IPL
Important address spaces started at Master Scheduler Initialization
time (MSI):
• SMF (System Management Facility)
• System Logger
• BCPii (Base Control Program internal interface)
z/OS Concepts #CC 169
A set of services that allow
special z/OS applications a way of
programmatically controlling the
mainframe hardware
configuration
159. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
z/OS Concepts #CC 170
Receives jobs, schedules them for
processing and handles their output
160. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
z/OS Concepts #CC 171
Security program used to protect
resources
161. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
• ICSF (Integrated Cryptographic Service Facility)
z/OS Concepts #CC 172
Provides the z/OS Cryptography interfaces
to applications: Enciphering, Deciphering,
Hashing, and Generating/verifying
digital signatures. Implements this via
both crypto hardware and software.
162. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
• ICSF (Integrated Cryptographic Service Facility)
• VTAM® (Virtual Telecommunications Access Method a.k.a. z/OS Communications Server)
z/OS Concepts #CC 173
Implements SNA (Systems Network
Architecture) with API (Application Program
Interface) for communicating with devices
and programs
163. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
• ICSF (Integrated Cryptographic Service Facility)
• VTAM® (Virtual Telecommunications Access Method a.k.a. z/OS Communications Server)
• TCAS (Terminal Control Address Space)
z/OS Concepts #CC 174
Communication interface for
TSO/E (Time Sharing
Option/Extensions)
164. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
• ICSF (Integrated Cryptographic Service Facility)
• VTAM® (Virtual Telecommunications Access Method a.k.a. z/OS Communications Server)
• TCAS (Terminal Control Address Space)
• TCP/IP (Transmission Control Protocol/Internet Protocol a.k.a. z/OS Communications
Server: IP)
z/OS Concepts #CC 175
Networking protocols for computer
communications
165. IBM Speak - IPL
Important started address spaces
• JES (Job Entry Subsystem a.k.a. JES2 or JES3)
• RACF® (Resource Access Control Facility a.k.a. z/OS Security Server)
• VTAM® (Virtual Telecommunications Access Method a.k.a. z/OS Communications Server)
• TCAS (Terminal Control Address Space)
• TCP/IP (Transmission Control Protocol/Internet Protocol a.k.a. z/OS Communications
Server: IP)
z/OS Concepts #CC 176
Once TCP/IP is initialized,
the IPL is considered
complete
166. IBM Speak - IPL
• Of course there is still more work to be done
• Middleware and application products like the following need to be
started:
• SA z/OS (System Automation for z/OS)
• DB2® (Data Base 2)
• CICS® Transaction Server for z/OS (Customer Information Control System)
• IMS™ (Information Management System)
• WAS (WebSphere® Application Server)
z/OS Concepts #CC 177
168. IBM Speak – Parallel Sysplex
• A sysplex is
• A collection of z/OS systems that cooperate
• A Parallel Sysplex
• Is a sysplex that uses multisystem data-sharing technology
• Allows direct, concurrent read/write access to shared data from all systems
without impacting performance or data integrity
• Work requests that are associated with a single workload
• Can be dynamically distributed for parallel execution on systems
• Based on available processor capacity
•
z/OS Concepts #CC 179
169. IBM Speak – Parallel Sysplex
• In many ways a Parallel Sysplex appears as a single large system
• The collection of z/OS systems cooperate to:
• Process workloads
• Provide higher availability
• Provide easier systems management
• Provide improved growth
z/OS Concepts #CC 180
171. Parallel Sysplex
z/OS Concepts #CC 182
The z/OS
components that
manage the
sysplex are:
XCF (cross system
coupling facility)
XES (cross-system
extended services)
172. Parallel Sysplex
z/OS Concepts #CC 183
XCF allows authorized programs on one
system to communicate with programs on
the same system or on other systems
173. Parallel Sysplex (7 of 13)
z/OS Concepts #CC 184
XES enables applications and subsystems to
take advantage of the coupling facility
174. Parallel Sysplex
z/OS Concepts #CC 185
CF (Coupling Facility) provides:
• Data sharing across the systems in a sysplex
• Maintaining the integrity and consistency of
shared data
• Maintaining the availability of a sysplex
175. Parallel Sysplex
z/OS Concepts #CC 186
STP (Server Time Protocol) is required
to synchronize the TOD (time-of-day)
clocks for systems in a sysplex
177. Parallel Sysplex
z/OS Concepts #CC 188
Applications written to take advantage of a
parallel sysplex can have multiple
instances running on any/all z/OS images
Data accessible from all images
180. z/OS Concepts – Serialization
• Customers using z/OS may runs many concurrent programs and
many threads of the same program simultaneously.
• Think credit card transactions!
z/OS Concepts #CC 191
181. z/OS Concepts – Serialization
• Customers using z/OS may runs many concurrent programs and
many threads of the same program simultaneously.
• Think credit card transactions!
• What if these programs need to update resources at the same time?
z/OS Concepts #CC 192
182. z/OS Concepts – Serialization
• Customers using z/OS may runs many concurrent programs and
many threads of the same program simultaneously.
• Think credit card transactions!
• What if these programs need to update resources at the same time?
• Data sets
• Virtual resources
• Lists
• Queues
• Data areas (control blocks)
z/OS Concepts #CC 193
183. z/OS Concepts – Serialization
• Customers using z/OS may runs many concurrent programs and
many threads of the same program simultaneously.
• Think credit card transactions!
• What if these programs need to update resources at the same time?
• Data sets
• Virtual resources
• Lists
• Queues
• Data areas (control blocks)
• How do we ensure data integrity and fair access to these resources?
z/OS Concepts #CC 194
184. z/OS Concepts – Serialization
• Global Resource Serialization (GRS) is the z/OS component designed
to protect the integrity of resources in a multitasking, multi-host
environment
z/OS Concepts #CC 195
185. z/OS Concepts – Serialization
• Global Resource Serialization (GRS) is the z/OS element designed to
protect the integrity of resources in a multitasking, multi-host
environment
• Coordinates access to resources used by more than one program
z/OS Concepts #CC 196
186. z/OS Concepts – Serialization
• Global Resource Serialization (GRS) is the z/OS element designed
to protect the integrity of resources in a multitasking, multi-host
environment
• Coordinates access to resources used by more than one program
• Uses ENQs and Latches to scope resources at various levels:
• STEP – synchronize within a single address space
• SYSTEM – synchronize single system apps
• SYSTEMS – synchronize multisystem apps
• SYSPLEX – synchronize across a sysplex
• Custom (Latches) – synchronize within a multitasking, or multi-threaded
application
z/OS Concepts #CC 197
187. z/OS Concepts – Serialization
• Program obtains ENQ or Latch before reading or updating
protected resource
z/OS Concepts #CC 198
188. z/OS Concepts – Serialization
• Program obtains ENQ or Latch before updating protected
resource
• Determines if it should be exclusive (write access) or
shared (read/only access)
z/OS Concepts #CC 199
190. z/OS Concepts – Managing Workloads
• One of the strengths of the IBM Z platform and the z/OS operating
system is the ability to run multiple workloads at the same time
within one z/OS image or across multiple images.
z/OS Concepts #CC 201
191. z/OS Concepts – Managing Workloads
• One of the strengths of the IBM Z platform and the z/OS operating
system is the ability to run multiple workloads at the same time
within one z/OS image or across multiple images.
• z/OS needs to:
• Prioritize work
• Use the installation resources as efficiently as possible
• Maintain the highest possible throughput
• Achieve the best possible system responsiveness.
z/OS Concepts #CC 202
192. z/OS Concepts – Managing Workloads
• One of the strengths of the IBM Z platform and the z/OS operating
system is the ability to run multiple workloads at the same time
within one z/OS image or across multiple images.
• z/OS needs to:
• Prioritize work
• Use the installation resources as efficiently as possible
• Maintain the highest possible throughput
• Achieve the best possible system responsiveness.
• Dynamic workload management is accomplished through the
Workload Management (WLM) component of the z/OS operating
system
z/OS Concepts #CC 203
193. z/OS Concepts – Managing Workloads
• WLM allows a customer to define performance goals and assign a
business importance to each goal.
z/OS Concepts #CC 204
194. z/OS Concepts – Managing Workloads
• WLM allows a customer to define performance goals and assign a
business importance to each goal.
• Goals are defined in business terms, and the system decides how
much resource, such as CPU and storage, should be given to the work
to meet its goal.
z/OS Concepts #CC 205
195. z/OS Concepts – Managing Workloads
• WLM algorithms use the service definition information and internal
monitoring feedback to check how well they are doing in meeting the
goals.
• Algorithms periodically adjust the allocation of resource as the workload level
changes.
z/OS Concepts #CC 206
196. z/OS Concepts – Managing Workloads
• WLM algorithms use the service definition information and internal
monitoring feedback to check how well they are doing in meeting the
goals.
• Algorithms periodically adjust the allocation of resource as the workload level
changes.
• For each system, WLM manages the system resources.
• Coordinates and shares performance information across the
sysplex.
• How well it manages one system is based on how well the other systems are also doing
in meeting the goals. If there is contention for resources, it makes the appropriate trade-
offs based on the importance of the work and how well the goals are being met.
z/OS Concepts #CC 207
197. z/OS Concepts – Managing Workloads
• WLM can dynamically start and stop server address spaces to
process work from application environments.
• On a single system or across the sysplex
• Batch initiators can be managed
• Can dynamically manage the number of batch initiators for one or more job classes to
meet the performance goals of the work.
z/OS Concepts #CC 208
198. z/OS Concepts – Managing Workloads
• WLM can dynamically start and stop server address spaces to
process work from application environments.
• On a single system or across the sysplex
• Batch initiators can be managed
• Can dynamically manage the number of batch initiators for one or more job classes to meet
the performance goals of the work.
• WLM also collects real-time performance data and delay monitoring.
• Available for performance monitors and reporters for integration into detailed
reports.
z/OS Concepts #CC 209
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