To set checkpoints, use job control statements and use
RERUN clause in the
RERUN clause with a particular COBOL
indicates that a checkpoint record is to be written to a checkpoint
data set whenever a specified number of records in the COBOL file
have been processed or when
END OF VOLUME is reached.
You cannot use the
RERUN clause with files that are
defined with the
You can write checkpoint records from several COBOL files to one checkpoint data set, but you must use a separate data set exclusively for checkpoint records. You cannot embed checkpoint records in one of your program data sets.
Restrictions: A checkpoint data set must have sequential organization. You cannot write checkpoints in VSAM data sets or in data sets that are allocated to extended-format QSAM data sets. Also, a checkpoint cannot be taken if any program in the run unit has an extended-format QSAM data set that is open.
records are written in the checkpoint data set defined by a
DD statement, you also choose the checkpoint
- Single (store single checkpoints)
one checkpoint record exists at any given time. After the first checkpoint
record is written, any succeeding checkpoint record overlays the previous
This method is acceptable for most programs. You save space in the checkpoint data set, and you can restart your program at the latest checkpoint.
- Multiple (store multiple contiguous checkpoints)
are recorded and numbered sequentially. Each checkpoint is saved.
Use this method if you want to restart a program at a checkpoint other than the latest one taken.
You must use the multiple checkpoint method for complete compliance with the 85 COBOL Standard.
Checkpoints during sort operations have the following requirements:
- If checkpoints are to be taken during a sort operation, add a
SORTCKPTin the job control procedure for execution.
- You can take checkpoint records on ASCII-collated sorts, but the system-name that indicates the checkpoint data set must not specify an ASCII file.
Using checkpoint/restart with DFSORT
Testing for a successful checkpoint
DD statements for defining checkpoint data sets