Checkpointing

The writing of checkpoint records is initiated by the user with the aid of the RERUN clause. The user can determine the point in time when the checkpoint records are to be written; for a given file, checkpointing is possible at each reel swapping, or after the processing of a specific number of records of that file.

Format 1 of the RERUN clause (extract; for a complete description, see “COBOL2000 Reference Manual” [1]):

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RERUN [ON implementor-name] EVERY {END OF {REEL | UNIT} | integer-1 RECORDS} OF file-name


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implementor-name

Specified as SYSnnn (0 <= nnn <= 244)
COBOL2000 generates either one or two checkpoint files:

1. One checkpoint file if nnn <= 200.
   COBOL2000 forms the standard name progid.RERUN.SYSnnn as well as the link name SYSnnn.
   Checkpoint records are written to this file continuously. At end of file, additional storage space is requested internally.

2. Two checkpoint files, if nnn > 200.
   COBOL2000 forms the standard names progid.RERUN.SYS.nnnA,
   progid.RERUN.SYS.nnnB and the link names SYSnnnA and SYSnnnB.Checkpoint records are written to each of the two files alternately; any previously written checkpoint record will be overwritten.

Format 2 of the RERUN clause is permitted for sort files only; it is therefore described in section "Checkpointing and restart for sort programs".
After each successful output of a checkpoint record, information necessary for a possible restart will be displayed on SYSOUT.

Message format:

E301 CHECKPOINT#aa, HALF PAGE#=bb, DATE=cc, TIME=dd:ee

aa bb cc dd ee

checkpoint number PAM page number mm/dd/yy:month/day/year hour minute