Has your application or WebSphere MQ for z/OS stopped processing work?

There are several reasons why your system would unexpectedly stop processing work. These include:

Queue manager problems
The queue manager could be shutting down.
Application problems
An application programming error could mean that the program branches away from its normal processing, or the application could get in a loop. There could also have been an application abend.
WebSphere MQ problems
Your queues could have become disabled for MQPUT or MQGET calls, the dead-letter queue could be full, or WebSphere MQ for z/OS could be in a wait state, or a loop.
z/OS and other system problems
z/OS could be in a wait state, or CICS(R) or IMS(TM) could be in a wait state or a loop. There could be problems at the system or sysplex level that are affecting the queue manager or the channel initiator. For example, excessive paging. It could also indicate DASD problems, or higher priority tasks using a lot of CPU.
DB2(R) and RRS problems
Check that DB2 and RRS are active.

In all cases, carry out the following checks to determine the cause of the problem: