2. PERFORMANCE REPORTING ANALYSIS › 2.5 Virtual Storage Management Analysis › 2.5.4 Virtual Storage Concepts in MVS/XA

2.5.4 Virtual Storage Concepts in MVS/XA

The methodology section is an introduction to the concepts in
MVS/XA underlying Virtual Storage Manager (VSM) control of
available virtual storage and RMF measurement of its use.
Virtual storage is allocated in 4KB increments in
either the Common or Private Areas in response to requests
for GETMAINS for various subpools of storage.  These subpools
characterize whether the memory will be page-fixed or fetch-
protected, in what major area of virtual storage it will
exist, and the direction of allocation.  RMF can measure the
allocation and fragmentation of these portions of the Common
Area and of selected Private Areas.  The following sections
include discussions of each of these topics:

    1 - Virtual Storage Map for MVS/XA
    2 - Initialization and Management of Virtual Storage
    3 - VSM Management and Measurement Macros
    4 - Virtual Storage Subpools
    5 - Storage Protection
    6 - Virtual Storage Measurement by RMF
    7 - Allocation Measurements and Their Interpretation