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Browse Prior Art Database

Global PSM in MVS in a Data Space

IP.com Disclosure Number: IPCOM000102489D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Cox, D: AUTHOR [+3]

Abstract

This article describes the ability to support Global Persistent Storage Mechanism (PSM) in MVS across address spaces. Persistent Storage Mechanism is a memory management system for transaction programs. In OfficeVision/2 (OV/2) threads from different processes can share data though Global PSM. This enables processes to retain data in memory across the creation and destruction of tasks. Persistent Storage also allows data to be kept by key rather than by address pointer. This capability is needed within OV/MVS to enable code from OV/2 to be ported to MVS.

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This is the abbreviated version, containing approximately 68% of the total text.

Global PSM in MVS in a Data Space

       This article describes the ability to support Global
Persistent Storage Mechanism (PSM) in MVS across address spaces.
Persistent Storage Mechanism is a memory management system for
transaction programs. In OfficeVision/2 (OV/2) threads from different
processes can share data though Global PSM. This enables processes to
retain data in memory across the creation and destruction of tasks.
Persistent Storage also allows data to be kept by key rather than by
address pointer. This capability is needed within OV/MVS to enable
code from OV/2 to be ported to MVS.

      The solution is to provide a Global Persistent Storage
Mechanism for address spaces in MVS. The Global PSM structure mimics
the structure within OV/2. The location of the Global PSM must be
different in MVS from OS/2*. In OS/2 each thread and process has the
potential to access all segments of memory in the system. In MVS,
memory is either private to the address space or common to all
address spaces in the system. The Common Storage Area (CSA) or
Extended Common Storage Area (ECSA) is at a premium in the system as
it is a limited resource.  To enable PSM to avoid this resource
constraint, Global PSM is kept in a separate address space, called a
data space. The data space is a feature of MVS/ESA*.  Address Spaces
can access the data space through Cross Memory Services, another
feature of MVS/ESA.  To control access to the data kept in Global
PSM, only PSM modules ar...