It might be necessary for you to create control blocks that your installation will use while APPC/MVS is processing the transaction program. To create installation-specific control blocks:

1. Create a DSECT for your installation's control block
2. In Exit 43:
   1. Include all the control blocks necessary for the exit. Mapping macros normally required in the Environment section identifies all the control blocks IBM® suggests should be included. Be sure to include any installation-specific control blocks you have created for TPs.
   2. Issue a $GETMAIN macro to obtain storage for the control block.
   3. Initialize the control block with the required information.
   4. Use the information as required while JES2 processes the transaction program.

Your installation might want to issue installation-defined messages to the TP message log when either JES2 selects or terminates a transaction program. Code the following macro to issue a message in Exit 43:

$WTO ROUTE=$LOG