Two-phase commit for DBCTL

DBCTL uses a two-phase commit to record a syncpoint. At the completion of a two-phase commit, the requested processing is committed and if a failure occurs, DBCTL does not ABORT committed changes.

Two-phase commit consists of the PREPARE and COMMIT phases. Within the PREPARE phase, CICS® issues a PREPARE request to DBCTL. DBCTL writes to the log and issues its response to the PREPARE request to CICS. Within the COMMIT phase, there are two possible actions: COMMIT and ABORT. The ABORT action for data belonging to full function DL/I databases is backout. There is no backout for data belonging to DEDBs because it is not written to the database before the COMMIT phase. The effect of an ABORT for DEDBs is also referred to as undo. Because a CICS thread may be accessing data belonging to both full function DL/I databases and DEDBs, we use the term ABORT to refer to both backout and undo.