The document provides an overview of memory allocation in programming, outlining its two main types: static and dynamic memory allocation. It explains how memory is assigned during runtime and details stack-based and heap-based memory allocation methods, including the behaviors and structures associated with each. Finally, it describes how the operating system manages memory allocation when creating processes for executing programs.

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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