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OMPE Subsystem Common Virtual Storage Manager

IP.com Disclosure Number: IPCOM000216957D
Publication Date: 2012-Apr-25
Document File: 6 page(s) / 62K

Publishing Venue

The IP.com Prior Art Database

Abstract

A common storage manager for Z/OS® is disclosed.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 32% of the total text.

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OMPE Subsystem Common Virtual Storage Manager

Disclosed is a common storage manager for Z/OS®.

Common virtual storage is shared by z/OS operating system components, including IBM® and original equipment manufacturer (OEM) program products. It is used to define control structures that contain data that is required to persist for the life of an address space or for the life of the z/OS operating system. The amount of common virtual storage defined to the z/OS operating system is determined by the user when the operating system is IPL'd, and it cannot change without re-IPLing the operating system.

The z/OS operating system uses common virtual storage designated as the Extended/System Queue Area (E/SQA) to build control structures required to manage system and non-system address spaces. IBM and OEM program products [mostly] use common virtual memory designated as the Extended/Common Service Area (E/CSA).

E/SQA and E/CSA virtual storage is explicitly assigned and explicitly freed. For example, a component program that acquires 4K of E/CSA virtual storage must free it when it no longer needs it. Because the z/OS operating system will not free the 4K E/CSA virtual storage when the component program normally or abnormally terminates it is the responsibility of the acquiring component to free it, when there's no need for the 4K E/CSA virtual storage to persist for the life of the address space
or the life of the operating system.

It's inherent in any IBM and OEM product to have E/SQA and E/CSA virtual storage leaks. In z/OS a storage leak occurs when a program obtains virtual storage and due to programming bugs the virtual storage is not released. Virtual storage leaks eventually cause system-wide common virtual storage shortages that cause program products to abnormally terminate when additional common virtual storage is requested. Furthermore, common virtual storage shortages may cause the entire operating system to crash.

E/SQA and E/CSA virtual storage is acquired and released by invoking one of the following z/OS operating system macros:

STORAGE OBTAIN/RELEASE


GETMAIN/FREEMAIN

The OMEGAMON Collector secondary z/OS subsystem implements its own version of the above macros as follows:

$STORAGE OBTAIN/RELEASE


$GETMAIN/$FREMAIN

The OMEGAMON program products can invoke these macros to specify additional attributes that determine E/SQA and E/CSA virtual storage persistence. The attributes are:

FREE=EOT


FREE=EOM

The ability for any program product to use the FREE=[EOT|EOM] attributes will with minor programming effort drastically reduce common virtual storage shortages that impact many customer environments.

Reliability, Availability, and Serviceability (RAS) to IBM customers can be severely diminished due to common virtual storage shortages whether IBM or EOM program products related, causing system

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critical application outages.

The common virtual storage manager component of the OMEGAMON Collector operates under a z/OS seco...