Controlling unilateral decisions about pending work units

IMS allows system definition to allow resynchronization without regard to inbound sequence number mismatches (OPTIONS=FORCSESS on the TERMINAL macro statement or an ETO user descriptor), or to only allow resynchronization when the inbound sequence numbers agree (OPTIONS=SYNCSESS). A keyword on the IMS /CHANGE command allows an authorized terminal operator to override the system definition specification for a single attempt to initiate a session. The effects of the CHANGE command are reset to the original system definition specification after one session initiation attempt. IMS does allow unilateral decisions to back out during session outages. However, using the IMS /DEQUEUE command for a session (terminal, and optionally, the subpool parameter) or LTERM during a session outage where an output-message sync point is pending is considered to be a unilateral decision by an authorized terminal operator to commit the pending output.

A pending output sync-point response can be determined by using the IMS /DISPLAY command. When two IMS subsystems are connected by an ISC session, the FORCSESS option must be in effect on the opposite IMS subsystem from one where a pending output message was dequeued (committed) using a /DEQUEUE command, or session resynchronization fails with message DFS2065. Using FORCESS rather than SYNCSESS has no other effect between two IMS subsystems.