[z/OS]

Dealing with performance problems on z/OS

Use this topic to investigate IBM® MQ for z/OS® performance problems in more detail.

Performance problems are characterized by the following:
  • Poor response times in online transactions
  • Batch jobs taking a long time to complete
  • The transmission of messages is slow

Performance problems can be caused by many factors, from a lack of resource in the z/OS system as a whole, to poor application design.

Remote queuing problems can be due to network congestion and other network problems. They can also be caused by problems at the remote queue manager.

IBM MQ for z/OS system considerations

The z/OS system is an area that requires examination when investigating performance problems.

You might already be aware that your z/OS system is under stress because these problems affect many subsystems and applications.

You can use the standard monitoring tools such as Resource Monitoring Facility ( RMF ) to monitor and diagnose these problems. They might include:
  • Constraints on storage (paging)
  • Constraints on processor cycles
  • Constraints on DASD
  • Channel path usage

Use normal z/OS tuning techniques to resolve these problems.

CICS constraints

CICS® constraints can also have an adverse effect on IBM MQ for z/OS performance. Use this information for further details about CICS constraints.

Performance of IBM MQ tasks can be affected by CICS constraints. For example, your system might have reached MAXTASK, forcing transactions to wait, or the CICS system might be short on storage. For example, CICS might not be scheduling transactions because the number of concurrent tasks has been reached, or CICS has detected a resource problem. If you suspect that CICS is causing your performance problems (for example because batch and TSO jobs run successfully, but your CICS tasks time out, or have poor response times), see the CICS Problem Determination Guide and the CICS Performance Guide.

Note: CICS I/O to transient data extrapartition data sets uses the z/OS RESERVE command. This could affect I/O to other data sets on the same volume.