This is an PPT of Operating System. It include the following topic "Memory Allocation to a process ".

1. Presented By:
SATYA PRAKASH RANJAN
MCA/25005/18

2. CONTENTS
 What is memory allocation?
 Types of memory allocation
 Use of stack
 Use of heap
 Memory allocation model
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3. Meaning of memory allocation
 Processes are assigned a specific memory as
per their requirements during their run-
time.
 When the program is finished its operation
or is idle, the memory is released and
allocated to another program or merged
within the primary memory.
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4. Types of memory allocation
 Memory allocation has two core types;
 Static Memory Allocation:
 Memory allocated at compile time.
 Dynamic Memory Allocation:
 Memory allocated at run time.
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Static vs Dynamic allocation

6. Memory assignment
 Memory assignment usually follow these 2 type of
Data Structures based on the need and use cases
 Stack Based
 Heap Based
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7. Stack based memory assignment
 Allocated memory includes variables whose scope is
associated with functions, procedures, or blocks, in a
program and parameters of function calls.
 Memory is allocated when a function or block is
entered and is deallocated when it is exited.
 Last-In First-Out (LIFO) nature of the
allocation/deallocation of data leads to Stack based
allocation
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8.  Each entry in stack is of some standard size e.g. N bytes
 A contiguous area of memory is reserved for the stack.
 Only the last entry of the stack is accessible at any time.
 Stack data is used to support function calls during
execution
 The group of stack entries that pertain to one function
call is called a stack frame.
 Stack frame is pushed on the stack during function call
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9.  Two provisions are made to facilitate use of stack
frames:
 The first entry in a stack frame is a pointer to the
previous stack frame on the stack. This entry facilitates
popping off of a stack frame.
 A pointer called the frame base (FB) is used to point
to the start of the topmost stack frame in the
stack.
 It helps in accessing various stack entries in the
stack frame.
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10. Heap based memory assignment
 The program-controlled dynamic data (PCD data) of
the program is allocated by using Heap
 Heap allows allocation/de-allocation of memory in
random order
 An allocation request by a process returns with a
pointer to the allocated memory area in the heap, and
the process accesses the allocated memory area
through this pointer.
 A de-allocation request returns a pointer to the
memory area to be de-allocated.
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11. Memory allocation model for a
process
 The kernel creates a new process when a user issues a
command to execute a program.
 At this time, it also decides how much memory it
should allocate to the process
 Process needs memory for following components:
 Code and static data of the program
 Stack
 Program-controlled dynamic data (PCD data)
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13. Thank You!!!
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