Environment-dependent WebSphere MQ for z/OS functions

The main differences to be considered between WebSphere MQ functions in the environments in which WebSphere MQ for z/OS runs are:

• WebSphere MQ for z/OS supplies the following trigger monitors:
  • CKTI for use in the CICS environment
  • CSQQTRMN for use in the IMS environment

  You must write your own module to start applications in other environments.

• Syncpointing using two-phase commit is supported in the CICS and IMS environments. It is also supported in the z/OS batch environment using transaction management and recoverable resource manager services (RRS). Single-phase commit is supported in the z/OS environment by WebSphere MQ itself.
• For the batch and IMS environments, the MQI provides calls to connect programs to, and to disconnect them from, a queue manager. Programs can connect to more than one queue manager.
• A CICS system can connect to only one queue manager. This can be made to happen when CICS is initiated if the subsystem name is defined in the CICS system start-up job. The MQI connect and disconnect calls are tolerated, but have no effect, in the CICS environment.
• The API-crossing exit allows a program to intervene in the processing of all MQI calls. This exit is available in the CICS environment only.
• In CICS on multiprocessor systems, some performance advantage is gained because MQI calls can be executed under multiple z/OS TCBs. For more information, see the WebSphere MQ for z/OS Concepts and Planning Guide.

These features are summarized in Table 13.

Table 13. z/OS environmental features