A key feature of CICS® VT
is that your application programs are unchanged although your VSAM data is migrated to
DB2®. In practice, there may be situations when some minor program changes overcome
operational or performance issues. Typical situations that may benefit from minor application changes are:
- Long running CICS transactions that do not issue SYNCPOINTs on a regular basis
may cause DB2 deadlocks or timeouts. Row-level locking may help, but it may be necessary to add SYNCPOINT
calls to offending application programs.
- Batch programs that use REPRO, SORT and SYNCSORT work with
CICS VT, but it may
make more sense to use equivalent DB2 utilities to achieve optimal performance, especially for large files.
- Batch programs that issue many UPDATE commands may cause contention issues with other
DB2 tasks, and may exceed NUMLKTS and NUMLKUS limits that are defined in your DSNZPARM.
One solution may be to add SQL COMMIT calls to your application program. This is discussed in
Adding SQL commit calls
If you are aware of any long running
CICS
transactions, or are migrating large files that are updated heavily by batch programs,
you should include the possibility of minor application program changes in your migration planning.