Limitations of intra-group queuing

The limitations of intra-group queuing are: messages eligible for transfer using intra-group queuing, number of intra-group queuing agents per queue manager, and starting and stopping the intra-group queuing agent.

This topic describes the limitations of intra-group queuing.

Messages eligible for transfer using intra-group queuing

Because intra-group queuing uses a shared transmission queue that is defined in the coupling facility (CF), intra-group queuing is limited to delivering messages of the maximum supported message length for shared queues minus the length of a transmission queue header (MQXQH).

Number of intra-group queuing agents per queue manager

Only one IGQ agent is started per queue manager in a queue sharing group.

Starting and stopping the intra-group queuing agent

The IGQ agent is started during queue manager initialization and terminated during queue manager shut-down. It is designed to be a long running, self recovering (in the event of abnormal termination), task. If there is an error with the definition of the SYSTEM.QSG.TRANSMIT.QUEUE (for example, if this queue is Get inhibited) the IGQ agent keeps retrying. If the IGQ agent encounters an error that results in normal termination of the agent while the queue manager is still active, it can be restarted by issuing an ALTER QMGR IGQ(ENABLED) command. This command avoids the need to recycle the queue manager.

Set the queue manager attribute IGQ to ENABLED or DISABLED

If the queue manager attribute IGQ is set to ENABLED or DISABLED, existing object handles may be invalidated with reason code MQRC_OBJECT_CHANGED. See Get started with intra-group queueing for more information.