RLS locks

For files opened in RLS mode, VSAM maintains a single central lock structure using the lock-assist mechanism of the MVS™ coupling facility. This central lock structure provides sysplex-wide locking at a record level.

The locks for files accessed in non-RLS mode, the scope of which is limited to a single CICS® region, are CI locks. However, the CICS enqueue domain also holds a record lock for the record accessed within the CI.

For coupling facility data tables that are updated under the locking model, the coupling facility data table server stores the lock with its record in the CFDT. As in the case of RLS locks, storing the lock with its record in the coupling facility list structure that holds the coupling facility data table ensures sysplex-wide locking at record level.

For both RLS and non-RLS recoverable files, CICS releases all locks on completion of a unit of work. For recoverable coupling facility data tables, the locks are released on completion of a unit of work by the CFDT server.