Is a queue, page set, or Coupling Facility structure filling up unexpectedly?

This could indicate that an application is looping, and putting messages on to a queue. (This could be a batch, CICS, or TSO application.)

Identifying a looping application

In a busy system, it might be difficult to identify which application is causing the problem. If you keep a cross-reference of applications to queues, terminate any programs or transactions that could be putting messages on to the queue, and investigate these programs or transactions before using them again. (The most likely culprits will be new, or changed applications; check your change log to identify them.)

Try issuing a DISPLAY QSTATUS command on the queue. This will give you information about the queue that might help to identify which application is looping.

Incorrect triggering definitions

It might be that a getting application has not been triggered due to incorrect object definitions, for example, the queue might be set to NOTRIGGER.

Distributed queuing

Using distributed queuing, a symptom of this problem could be a message in the receiving system indicating that MQPUT calls to the dead-letter queue are failing. This could be because the dead-letter queue has also filled up. The dead-letter queue message header (dead-letter header structure) contains a reason or feedback code explaining why the message could not be put on to the target queue. See the WebSphere MQ Application Programming Reference manual for information about the dead-letter header structure.

Allocation of queues to page sets

If a particular page set frequently fills up, there could be a problem with the allocation of queues to page sets. Refer to Distribution of queues on page sets for more information.

Shared queues

Is the Coupling Facility structure full? The z/OS command DISPLAY CF displays information about Coupling Facility storage including the total amount, the total in use, and the total free control and noncontrol storage. The RMF Coupling Facility Usage Summary Report provides a more permanent copy of this information.