Accessing the RECON data sets in parallel mode
You can access the RECON data sets in parallel mode to avoid data set deadlock situations.
The following terms are used in the topics related to parallel mode:
- DBRC group
- One or more DBRC instances that share a single RECON data set in an IMSplex environment.
- DBRC group ID
- The identifier of a DBRC group
- DBRC request
- Each action asked of DBRC (command process, query, and update) by IMS, DBRC application programs, and jobs.
DBRC uses the Transactional VSAM function of DFSMS to provide parallel access to the RECON data set. Transactional VSAM uses:
- The two-phase commit and backout service provided by z/OS® Resource Recovery Services to ensure that either all of the changes made by a transaction are hardened or all of the changes made by a transaction are backed out.
- A coupling facility (CF) for buffer caching, locking, and logging services.
Use the following commands to set the RECON data set access mode
to either serial or parallel:
- For a new RECON data set, use a INIT.RECON ACCESS(SERIAL or PARALLEL) command.
- For an existing RECON data set, use a CHANGE.RECON ACCESS(SERIAL or PARALLEL) command.
Before parallel RECON data set access can be enabled, both of the following conditions must be true:
- All DBRC instances that are accessing the RECON data set belong to a DBRC group with a unique DBRC group ID.
- All DBRC instances that are accessing the RECON data set are registered to Structured Call Interface (SCI), similar to the situation where RECON Loss Notification is involved. DBRC registers with SCI using the group ID as the member subtype.