Debugging facilities, syncpoint support, and recovery support

Use this information to learn about program debugging facilities, syncpoint support, and recovery support.

Program debugging facilities

IBM MQ for z/OS provides a trace facility used to debug your programs in all environments.

• The CICS Execution Diagnostic Facility (CEDF)
• The CICS Trace Control Transaction (CETR)
• The IBM MQ for z/OS API-crossing exit

On the z/OS platform, we can use any available interactive debugging tool that is supported by the programming language that we are using.

Syncpoint support

Synchronizing the start and end of units of work is necessary in a transaction processing environment so that transaction processing can be used safely.

This is fully supported by IBM MQ for z/OS in the CICS and IMS environments. Full support means cooperation between resource managers so that units of work can be committed or backed out in unison, under control of CICS or IMS. Examples of resource managers are Db2, CICS File Control, IMS, and IBM MQ for z/OS.

z/OS batch applications can use IBM MQ for z/OS calls to give a single-phase commit facility. This means that an application-defined set of queue operations can be committed, or backed out, without reference to other resource managers.

Two-phase commit is also supported in the z/OS batch environment using transaction management and recoverable resource manager services (RRS). For further information see Syncpoints in z/OS batch applications.

Recovery support

If the connection between a queue manager and a CICS or IMS system is broken during a transaction, some units of work might not be backed out successfully.

However, these units of work are resolved by the queue manager (under the control of the syncpoint manager) when its connection with the CICS or IMS system is reestablished.