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Updating Techniques, SYNCPOINT, and Logging

Updating Techniques, SYNCPOINT, and Logging

To maintain the most efficient and functional transaction processing environment, minimize the length of time your applications hold data with exclusive control (data locks). A transaction (task) that waits on a response from the terminal operator is called a conversational transaction. If your application locks data while waiting for an operator response, other users requesting a read for update of that data must wait until the transaction releases the data. For best overall performance, when writing CICS transactions do not lock the data you want to update while waiting for a response from an operator.

In addition to not waiting on the terminal, performance can be gained by issuing the following commands as late as possible in the processing of the transaction:

When updating a database in a CICS environment, pseudo conversational mode is the recommended method.

To perform a pseudo conversational transaction

  1. Read the target record without locking it.
  2. Save the record information in a temporary location.
  3. Display the record information to the screen.
  4. Obtain the updates to the information.
  5. Reread the target record with a lock.
  6. Verify that the locked record information is the same as the original information then write the updated information to the locked record.

    If the locked record information differs from the original information, release the record and return to step 2, if desired.

  7. Issue SYNCPOINT or end the transaction.

If a long running conversational transaction is needed, issue frequent SYNCPOINTs after updating records to increase efficiency. Task completion automatically generates a SYNCPOINT. A task ABEND generates a SYNCPOINT ROLLBACK provided there is no ABEND HANDLER.

Use SYNCPOINTs instead of CA Datacom/DB log (LOGxx) commands. Whenever possible, avoid using LOGxx commands (including COMIT and ROLBK) in a CICS environment.

This section contains the following topics:

Using CICS SYNCPOINT

Special Logging Commands Considerations