Requirements of the two-phase commit process

Requirements of the two-phase commit process when we use the CICS two-phase commit process with IBM MQ . These requirements do not apply to z/OS .

Note the following requirements:

• IBM MQ and CICS must reside on the same physical machine.
• IBM MQ does not support CICS on an IBM MQ MQI client.
• We must start the queue manager, with its name specified in the XAD resource definition stanza, before you attempt to start CICS. Failure to do this will prevent you from starting CICS if you have added an XAD resource definition stanza for IBM MQ to the CICS region.
• Only one IBM MQ queue manager can be accessed at a time from a single CICS region.
• A CICS transaction must issue an MQCONN request before it can access IBM MQ resources. The MQCONN call must specify the name of the IBM MQ queue manager specified on the XAOpen entry of the XAD resource definition stanza for the CICS region. If this entry is blank, the MQCONN request must specify the default queue manager.
• A CICS transaction that accesses IBM MQ resources must issue an MQDISC call from the transaction before returning to CICS. Failure to do this might mean that the CICS application server is still connected, leaving queues open. Additionally, if we do not install a task termination exit (see Sample task termination exit ), the CICS application server might later end abnormally, perhaps during a subsequent transaction.
• We must ensure that the CICS user ID (cics) is a member of the mqm group, so that the CICS code has the authority to call IBM MQ. For transactions running in a CICS environment, the queue manager adapts its methods of authorization and determining context as follows:
  • The queue manager queries the user ID under which CICS runs the transaction. This is the user ID checked by the Object Authority Manager, and is used for context information.
  • In the message context, the application type is MQAT_CICS.
  • The application name in the context is copied from the CICS transaction name.

Parent topic: Use CICS