Several elements of the CICS® infrastructure
now use 31-bit (above-the-line) storage in the CICS region, in place
of 24-bit (below-the-line) storage. Lowering the demands on 24-bit
storage helps avoid short-on-storage conditions and can reduce the
need for additional CICS regions.
The CICS runtime environment
is improved in the following ways:
- The need for additional CICS regions
to resolve demands on 24-bit storage is reduced.
- Problems caused by short-on-storage conditions in 24-bit storage
are avoided.
- CICS regions can carry
out simultaneous processing of a greater number of tasks that use
these CICS infrastructure items.
The following CICS infrastructure
items now use 31-bit storage (above 16 MB but below 2 GB) in place
of all, or some, of the 24-bit storage (below 16 MB) that was used
in previous releases:
- Communication areas (COMMAREAs) used with an
XCTL command, when the receiver is AMODE(31)
- Processing for transient data EXEC CICS application programming commands, wherever
possible
- Processing for journaling EXEC CICS application programming commands
- Processing for transaction
dumps and for the EXEC CICS DUMP
TRANSACTION command
- Access to QSAM to write data to extrapartition
transient data destinations (as a result of this change, subpool DFHTDG24
has been removed)
- Exit program link (EPL) control blocks
- Console write-to-operator transaction
(CWTO)
- Error message writer
- Sync point and backout processing
- Shutdown processing
- CICS execution diagnostic
facility (CEDF)
- CICS
command-language tables for command interpreter (CECI) and other functions
- Processing for function-shipped DL/I
calls
- Enable and disable functions for
work queues for interregion communication
- Opening of the z/OS® Communications Server ACB
- ECI over TCP/IP listener task (CIEP)
- Interregion communication control task (CSNC)
- Transaction environment transaction (CSXM)
- Global work area for the CICS DB2® task-related
user exit
- Global work area for the CICS IMS™ DBCTL
task-related user exit
- Global work area for the CICS WebSphere® MQ task-related user exit
- Enable function for global user exits
for emergency restart processing
- Mirror transactions (CEHP, CEHS,
CPMI, CSHR, CSMI, CSM1, CSM2, CSM3, CSM5, and CVMI)
Mirror transaction abends
The CICS-supplied
mirror transactions use 31-bit storage (above 16 MB but below 2 GB).
If an
EXEC CICS LINK command is issued over DPL
for an AMODE(24) application, an AEZA or AEZC abend will occur. To
avoid this situation, do one of the following:
- Define your own mirror transaction that uses 24-bit storage. For
example, you can copy a CICS-supplied mirror transaction, then specify
the TASKDATALOC(BELOW) attribute.
- Modify the application so that it is AMODE(31) and update the
appropriate program definition.
For more information, see Application programming for CICS DPL.
Last updated: Thursday, 27 June 2019