Chapter 10 Storage management

• Elements requiring storage

• Programmer and system controlled storage

• Static Storage Management

• Heap Storage Management

Elements requiring storage

• Code segments for translated user programs

• System run-time programs - e.g. libraries• User defined data structures and

constants• Subprogram return points• Referencing environments

Elements requiring storage

• Temporaries in expression evaluation

• Temporaries in parameter transmission

• Input-Output buffers• Miscellaneous system data - tables

etc

Operations that require storage allocation

• Subprogram call and return operations - creation and deletion of activation records

• Explicit data structure creation and destruction operations

• Component insertion and deletion operations

Programmer and system controlled storage

Pros and cons:Programmer knows when to allocate / free storage.

Programmer may interfere with the system-controlled storage management

Storage-Management PhasesInitial allocationRecoveryCompaction and reuse

Static Storage Management

Static allocation : allocation during translation that remains fixed throughout execution.

Does not allow recursive subprograms

Dynamic Allocation:Heap Storage Management

Memory used for dynamic allocation of data objects in somewhat unstructured manner is called heap storage.

OS

HEAP

STACK

Heap Storage ManagementTasks:

allocation, recovery,

dangling referencesgarbage collection

compaction, reuse

Fixed size elementsVariable size elements

Heap Compaction

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Heap Compaction

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