Improved queue manager scalability for IMS OTMA CM1 and APPC synchronous messages enhancement

The IMS 15 APAR PH51463 enhances queue manager scalability for IMS OTMA CM1 and APPC synchronous messages.

To avoid a queue manager buffer shortage when processing large (multi-record) messages in a shared queue environment, Queue Manager (QMGR) provides an option to cache the second through last records of multi-record messages in 64-bit storage when they are read from the shared queue structure. The types of messages that can be cached are:
  • APPC synchronous messages
  • OTMA CM1 (synchronous) messages
Messages of the supported types can be selected for caching by using the message record threshold. A message that is selected will have its second through last message cached in 64-bit storage. A message is selected for caching based on the following considerations:
  • Number of records - a message's records are cached when the number of records in the message is greater than a specified threshold. All messages with more than one record are cached when the queue pool has reached its highest upper limit.
  • 31-bit buffer allocation failure - a message will be cached when no 31-bit buffer is available. Any records already read into 31-bit buffers will be copied to 64-bit buffers, and the 31-bit buffers will be released.
IMS System Administrators can request QMGR 64-bit caching with several parameters in a new section of the DFSDFxxx PROCLIB member.

This enhancement is supported for IMS 15.3 and later. To activate it, apply PTF <PTF ID> for APAR PH51463.

Changes to commands

The attribute QMGRMESSAGECACHE is added to the list of pools allowed for the NAME() parameter in the QUERY POOL command.

For a list of the commands that are new or changed for this enhancement see the IMS commands row in the table in Documentation changes.

Documentation changes

The following table lists the publications that contain new or changed topics for the improved queue manager scalability for IMS OTMA CM1 and APPC synchronous messages enhancement. Publications that are not impacted by this enhancement are not included in the table.

Table 1. Links to topics that have new or changed content for this enhancement
Publication New or changed topics
Release planning IMS 15.4 enhancements IMS 15.4 system enhancements
System definition
IMS commands
IMS messages and codes