Coding a Checkpoint

The CHKPT macro instruction is coded in your program. When the CHKPT macro executes, job step information (about your program, virtual storage data areas, data set position, and supervisor control) is written as a checkpoint entry in a checkpoint data set. The point at which this information is saved becomes a checkpoint from which a restart may be performed. After the checkpoint entry is written, control returns to your program at the instruction following the CHKPT macro.

This chapter defines a checkpoint and explains how to establish checkpoints to restart job steps. Table 1 contains directive information about this chapter's contents:

Table 1. Chapter 2. Coding a Checkpoint
Section
When to Code a Checkpoint
Coding the DCB for a Checkpoint Data Set
Coding the DD Statement for a Checkpoint Data Set
Using Checkpoint Data Sets
Coding the CHKPT Macro Instruction
Canceling a Checkpoint
Serially Reusable Resources
Special Operating System Features