If you are using the CICS(R) adapter from a WebSphere MQ for z/OS system, ensure that CICS can obtain sufficient storage to accommodate messages up to 100 MB long.
A CICS system can have only one connection to a WebSphere MQ for z/OS queue manager, and this connection is managed by the WebSphere MQ for z/OS CICS adapter. The CICS adapter provides access to WebSphere MQ for z/OS resources for CICS programs.
In addition to providing access to the MQI calls, the adapter provides:
This section describes how the CICS adapter optimizes the performance of a CICS to WebSphere MQ connection.
There are a number of factors to consider when performance is critical:
Therefore, use the WAIT option with care.
To put multiple messages, use MQOPEN-MQPUT...MQPUT-MQCLOSE.
The EXEC CICS RETURN call accommodates all the work needed for syncpointing and task termination into one flow to WebSphere MQ instead of the two separate flows used when explicit syncpointing is used.
You can use the CKQC transaction to display statistics for the current connection.
The adapter supports a two-phase commit protocol for changes made to resources owned by WebSphere MQ for z/OS, with CICS acting as the syncpoint coordinator.
The CICS adapter also supplies facilities (for use by system programmers and administrators) for managing the CICS-WebSphere MQ for z/OS connection, and for collecting task and connection statistics. These facilities are described in the WebSphere MQ for z/OS System Administration Guide.
Application programmers can use trace points related to the MQI calls (for example, CSQCGMGD (get message data)) for debugging CICS application programs. System programmers can use trace points related to system events, such as recovery and task switching, for diagnosing system-related problems. For full details of trace points in the CICS adapter, see the WebSphere MQ for z/OS Problem Determination Guide.
Some trace data addresses are passed by applications. If the address of the trace data is in the private storage area of the CICS region, the contents of the area are traced when necessary. For example, this would be done for the trace entries CSQCGMGD (get message data) or CSQCPMGD (put message data). If the address is not in the private storage area, message CSQC416I is written to the CICS trace; this contains the address in error.
This section describes some of the things to consider with regard to CICS AEY9 and QLOP abends. For information about all other abends, see the WebSphere MQ for z/OS Messages and Codes.
A transaction does not abend with a CICS AEY9 code if it issues an MQI call before the adapter is enabled. Instead, it receives return code MQCC_FAILED and reason code MQRC_ADAPTER_NOT_AVAILABLE.
For more information about CICS AEY9 abends, see the CICS Messages and Codes.
Tasks abend with the abend code QLOP if a second MQI call is made after a call has been returned with completion code MQCC_FAILED and one of these reason codes:
This runaway mechanism can be activated only after the adapter has been enabled once. Before the adapter has been enabled, such a task loops with reason code set to MQRC_ADAPTER_NOT_AVAILABLE. To avoid this, ensure that your applications respond to the above reason codes either by terminating abnormally or by issuing an EXEC CICS SYNCPOINT ROLLBACK and terminating normally.
If the application does not terminate at this point, it might not issue any further WebSphere MQ calls even if the connection between WebSphere MQ and CICS is reestablished. Once WebSphere MQ is reconnected to CICS, new transactions can use MQI calls as before.
You can use the CICS execution diagnostic facility (CEDF) to monitor applications that use the CICS adapter. For details of how to use CEDF, see the CICS Application Programming Guide.
CEDF uses standard formatting to display MQI calls.
See WebSphere MQ for z/OS Problem Determination Guide for examples of the output produced by this facility.
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