Enterprise COBOL for z/OS, Version 4.2, Programming Guide

Interrupts and checkpoint/restart

When programs run for an extended period of time, interruptions might halt processing before the end of a job. The checkpoint/restart functions of z/OS allow an interrupted program to be restarted at the beginning of a job step or at a checkpoint that you have set.

Because the checkpoint/restart functions cause a lot of extra processing, use them only when you anticipate interruptions caused by machine malfunctions, input or output errors, or intentional operator intervention.

The checkpoint routine starts from the COBOL load module that contains your program. While your program is running, the checkpoint routine creates records at points that you have designated using the COBOL RERUN clause. A checkpoint record contains a snapshot of the information in the registers and main storage when the program reached the checkpoint.

The restart routine restarts an interrupted program. You can perform a restart at any time after the program was interrupted: either immediately (automatic restart), or later (deferred restart).

related tasks  
Setting checkpoints  
Restarting programs  
Resubmitting jobs for restart  
z/OS DFSMS: Checkpoint/Restart

related references  
DD statements for defining checkpoint data sets  
Messages generated during checkpoint  
Formats for requesting deferred restart



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