Environment-dependent IBM MQ for z/OS functions
Use this information when considering IBM® MQ for z/OS® functions.
The main differences to be considered between IBM MQ functions in the environments in which IBM MQ for z/OS runs are:
- IBM 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 IBM 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 startup 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 Planning on z/OS .
These features are summarized in Table 1.
| CICS | IMS | Batch/TSO | |
|---|---|---|---|
| Trigger monitor supplied | Yes | Yes | No |
| Two-phase commit | Yes | Yes | Yes |
| Single-phase commit | Yes | No | Yes |
| Connect/disconnect MQI calls | Tolerated | Yes | Yes |
| API-crossing exit | Yes | No | No |
Note: Two-phase commit is supported in the Batch/TSO environment using RRS.