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CA Datacom CICS Services Installation and Configuration Best Practices › Updating Techniques, SYNCPOINT, and Logging

Updating Techniques, SYNCPOINT, and Logging

Business Value

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 terminal response from the operator is called a conversational transaction. When waiting for an operator response, if your application locks data 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 to update while waiting for a response from an operator.

Additional Considerations

To avoid waiting on the terminal, you can help increase performance by issuing the following commands as late as possible in the processing of the transaction:

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

Note: A pseudoconversational transaction is a collection of tasks and transactions that appear to the end user as one task.

To perform a pseudoconversational 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 and end the transaction.
  4. Obtain the updates to the information upon entry of the new transaction.
  5. Reread the target record with a lock.
  6. Verify that the locked record information is the same as the original information, and 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. When no ABEND HANDLER exists, a task ABEND generates a SYNCPOINT ROLLBACK.

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