IBM MQ requests

At a high level, all processor-unique queues are maintained in system heap and IBM MQ memory to obtain extremely high access rates to z/TPF queues.

To assist with the recovery of persistent messages after a system IPL, the contents of all queues are checkpointed on a time-initiated basis to processor-unique DASD records. All updates made by using the MQPUT, MQPUT1, or MQGET functions between checkpoints are written to the recovery log.

The recovery log is used during restart for the recovery of IBM MQ requests that might have been in transition or lost. The size of the recovery log must be large enough to accommodate all logging activity for all z/TPF resource managers (not just the IBM MQ resource manager) between each successfully completed checkpoint. The checkpoint interval is 5 seconds. (If your z/TPF system is running under VPARS, the checkpoint interval is 1 second.) Enter the ZMQSC DISPLAY command with the QMGR parameter specified to view the number of seconds that were taken to complete the longest IBM MQ checkpoint since the last z/TPF system IPL. (This value is labeled CHECKPOINT HIGH WATER MARK in the display.) This value can help to ensure that your recovery log can accommodate all the necessary logging activity.

All processor shared queues are filed on z/TPF collection support (z/TPFCS).