With Two-phase commit, the CICS or IMS applications can access the database as a sync point participant. In this way, database updates are committed or rolled back through the use of CICS or IMS sync point services. The use of the sync point services guarantees that all updates performed within a logical unit of work will either all commit or all roll back. The database and the CICS or IMS Attachment Facilities support the sync point manager and its use of the Two-phase commit protocol. In the Two-phase commit protocol, CICS or IMS act as the coordinator, and the database acts as participants.
Two-phase commit applications must use a coordinator such as IMS or CICS. They cannot run as batch applications, unless the application provides its own coordinator.