Record Locking Strategies

MFDBFH supports the following types of record locking strategy:

Table Record Locking

Record locks are maintained in a separate lock table, and the associated lock behavior when using the COBOL READ, WRITE, and REWRITE verbs is the same as when accessing disk files via non-MFDBFH file handling operations or when using Fileshare. This is the default.

Database Record Locking

With this record locking strategy, MFDBFH makes use of the RDBMS to directly lock records in the file table. When records are locked this way, they will remain locked until the end of the current database transaction. This means that database record locking is restricted to being only available when using transactional files.

The benefit of using database record locking instead of table record locking is performance, but this comes at the cost of loss of compatibility with regular COBOL file I/O, and the inability to concurrently access the file non-transactionally (that is, a transactional file opened using the database record locking strategy by CICS cannot be shared with batch programs, which will open files non-transactionally).

To enable the database record locking strategy for transactional files, set the following environment variable:

MFDBFH_RECORD_LOCKING=database

In-memory Record Locking

This record locking strategy is used for I/O operations performed on files that have been allocated for exclusive use (that is, DISP=OLD, DISP=NEW, or DISP=MOD) in batch jobs running under an enterprise server region. This is the most performant of all of the record locking strategies.