Basic and Symbolic Checkpoint Calls

Basic CHKP Calls

The basic CHKP call is available from message-driven transactions as well as BMPs and batch programs. Basic CHKP commits the changes your program has made to the database and establishes places in your program from which you can restart your program in the event that it terminates abnormally.

Symbolic CHKP and XSRT Calls

Symbolic CHKP and XSRT calls are only available to BMPs and batch programs.

The symbolic CHKP call commits the changes your program has made to the database and establishes places in your program from which you can restart your program in the event that it terminates abnormally. In addition, the CHKP call:

• Works with the XRST call to restart your program if it terminates abnormally. An XRST call is required before a CHKP call to indicate to IMS that symbolic check points are being taken.
• Designates a checkpoint ID, which is a place within the program from which you can restart it should the program terminate abnormally.
• Designates up to seven data areas in your program to be automatically restored when your program is restarted after an abnormal termination.

The checkpoint ID and save areas are stored in files named IMSLOGR.DAT and IMSLOGR.IDX.

If an XRST call indicates that a restart should take place, the save areas are restored into the program's Working-Storage section. The restart checkpoint ID can be specified in the XRST call itself or as part of the Batch Program Command used to start the batch program. All XSRT calls, successful or not, are logged in the IMS System Log.

If an XSRT call indicates that a restart should take place, the save areas are restored into the program's Working-Storage. The restart checkpoint ID can be specified in the XRST call itself or as part of the Batch Program Command used to start the batch program. All restart calls, successful or not, are logged in the IMS System Log.