Synchronization level
The APPC synchronization level defines the protocol that is used when changing conversation states.
APPC and IMS support the following synchronization level values:
- SYNCLVL=NONE
- Specifies that the programs do not issue calls or recognize returned parameters relating to synchronization.
- SYNCLVL=CONFIRM
- Specifies that the programs can perform confirmation processing on the conversation.
- SYNCLVL=SYNCPT
- Specifies that the programs participate in coordinated commit processing on resources that are updated during the conversation under the z/OS® Resource Recovery Services (RRS) recovery platform. A conversation with this level is also called a protected conversation.
Additionally, either IMS or RRS can be specified as the synchronization point manager.
- RRS=Y
- If AOS=B, AOS=S, or AOS=X, transactions with SYNCLVL=NONE or CONFIRM are processed with IMS as the synchronization point manager.
If AOS=B or AOS=Y, transactions with SYNCLVL=SYNCPT are processed with RRS as the synchronization point manager.
In a shared message queue environment where the front-end IMS system is also the back-end IMS system, transactions with SYNCLVL=SYNCPT are processed with RRS as the synchronization point manager.
In a non-shared message queue environment, transactions with SYNCLVL=SYNCPT are processed with RRS as the synchronization point manager.
Restriction: The AOS= setting is applicable to shared message queue environment only. - RRS=N
- If AOS=B, AOS=S, or AOS=X, transactions with SYNCLVL=NONE or CONFIRM are processed with IMS as the synchronization point manager.
If the back-end IMS system has RRS=N specified, transactions with SYNCLVL=SYNCPT are processed only at the front-end IMS system. However, if the front-end IMS system also has RRS=N specified, transactions with SYNCLVL=SYNCPT are not processed at all.
Allocating a conversation with SYNCLVL=SYNCPT requires the RRS as the synchronization point manager. RRS controls the commitment of protected resources by coordinating the commit or backout request with the participating owners of the updated resources, the resource managers. IMS is the resource manager for DL/I, Fast Path data, and the IMS message queues. The application program decides whether the data is to be committed or aborted and communicates this decision to the synchronization point manager. The synchronization point manager then coordinates the actions in support of this decision among the resource managers.