12 IMS Version 8 Implementation Guide
Table 1-1 Estimated virtual storage constraint relief provided by IMS Version 8
1.4 Systems management enhancements
As IMS systems are joined together into sharing groups (sharing databases, network
resources, or message queues) in a sysplex environment, system management becomes
more complex. Prior to IMS Version 8, the IMSs that were in sharing groups had to be
managed individually. IMS Version 8 builds upon the idea of an IMS sysplex (known hereafter
as an IMSplex) to help reduce the complexity of managing multiple IMSs in a sysplex
environment.
An IMSplex can be defined as one or more IMS address spaces (control, manager, or server)
that work together as a unit. Typically (but not always), these address spaces:
򐂰 Share either databases or network resources or message queues (or any combination)
򐂰 Run in a S/390 sysplex environment
򐂰 Include an IMS Common Service Layer (CSL - new for IMS Version 8)
Note: The QSAV and AWE storage pools can expand during high volume processing.
Thus, the CSA saving shown in the following table is a minimum value of 8K (for QSAV)
and 12K (for AWE) per IMS subsystem. During high volume processing, these pools could
be significantly expanded, resulting in exhausting CSA and causing problems. By moving
these areas above the line the CSA problems may be avoided, thereby helping prevent
operating system crashes. So while the base system with no activity saves 8K and 12K,
the actual savings in the previously described situation, would be more.
Item Moved from
CSA to
Private
Moved from CSA to
ECSA
Moved from
ECSA to
Eprivate
Moved from
Private to
Eprivate
Checkpoint processor 54 KB
Restart processor 286 KB
FDBR modules 378 KB 420 KB
LPSTs (per IMS) 12 KB
QSAV areas (per IMS) 8 KB
System PSTs for a DB/DC
FP generated system
- or -
System PSTs for a DB/DC
system without FP
92 KB
- or -
28 KB
AWEs 12 KB
Part of each IMS log
buffer prefix
176 bytes per log
buffer, 352 bytes if dual
logging
Total 378 KB 112 KB (with FP) or
48 KB (without FP)
+
172 * BUFFNO (single
logging) or
352 * BUFFNO (dual
logging)
420 KB 352 KB
Chapter 1. Overview 13
The address spaces that can participate in the IMSplex are:
򐂰 Control region address spaces (CTL and DBRC)
򐂰 CSL address spaces (Operations Manager (OM), Resource Manager (RM), Structured
Call Interface (SCI))
򐂰 IMS server address spaces (CQS)
򐂰 Batch and utility regions using DBRC
򐂰 Automated operator programs and SPOCs
򐂰 Address spaces that serves as an interface between IMS and a protocol that is not directly
supported by IMS (for example, TCP/IP)
Examples of IMSplexes are:
򐂰 A set of IMS control regions at the Version 6, 7 or 8 level without a CSL that are sharing
data or sharing message queues
򐂰 A set of IMS control regions at the Version 8 level with a CSL that are sharing data or
sharing message queues
򐂰 A single IMS control region at the Version 8 level with a CSL. This still qualifies as an
IMSplex because it is a set of IMS address spaces (IMS control, CQS, SCI, OM, RM)
working together.
To support IMSplexes, a number of IMS functions have been enhanced and a number of new
functions have been added.
򐂰 The Base Primitive Environment (BPE) has been enhanced.
򐂰 The Common Queue Server (CQS) has been enhanced.
򐂰 A new component, the Common Service Layer (CSL), is introduced consisting of the
following three new address spaces:
Operations Manager (OM)
Resource Manager (RM)
Structured Call Interface (SCI)
򐂰 Optional Resource Structure.
򐂰 A TSO-based single point of control (SPOC) application program and a REXX API is
shipped with IMS Version 8.
򐂰 The IMS terminal management function of IMS TM has been enhanced.
򐂰 A new coordinated online change function has been added to coordinate global online
change activities of all the IMSs in the IMSplex.
The following sections briefly describe the enhancements that support the new IMSplexes
and the other systems management enhancements.
1.4.1 BPE enhancements
The Base Primitive Environment (BPE) has been enhanced to support the three new CSL
address spaces. Two new optional exits have been added and a new BPE command,
DISPLAY VERSION, which displays the version number of both the IMS component and the
BPE, is introduced.
Additional information on the Base Primitive Environment enhancements can be found in
Chapter 11, Base Primitive Environment enhancements on page 143.

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