COBOL Manual for TNS/E Programs (H06.03+)

Procedure Division Verbs
HP COBOL Manual for TNS/E Programs—520347-003
9-33
CHECKPOINT
checkpoint-list-name
is the name of a checkpoint list containing information that must be transferred to
the backup process. The checkpoint list is a COBOL record with a specific
structure in which the message changes are recorded. The information is returned
by these Saved Message Utility (SMU) routines:
For information on SMU routines and a description of the checkpoint list record, see
Saved Message Utility (SMU) Overview.
Usage Considerations:
•
Reason to Checkpoint
If a backup process takes over, the contents of items that are not checkpointed are
undefined.
•
Conditions Under Which Data Items Are Checkpointed
The compiler checkpoints only those data items that one or more CHECKPOINT
statements specify explicitly. These data items can be in either the Working-
Storage Section or the Extended-Storage Section.
•
Sending Values to a Backup Process
When CHECKPOINT executes, the values of the data items and file sync blocks
are sent to the fault-tolerant facility in the backup process. If the primary process
fails before another checkpoint is made, the backup begins processing from the
current checkpoint. The set of values specified in any checkpoint must be sufficient
for the backup process to continue processing correctly with only that information.
After the CHECKPOINT statement transfers the information in the checkpoint list to
the backup process, it resets the checkpoint list to empty and its storage space is
available to record further message changes.
•
Multiple Checkpoints for a Transaction
Use multiple checkpoints for a transaction if the number of WRITE statements
executed for a file exceeds the value of the sync depth with which the file was
opened. If a file was opened with sync depth n, use at least one CHECKPOINT for
every n WRITE statements executed for a file.
ALTERPARAMTEXT DELETESTARTUP PUTPARAMTEXT
DELETEASSIGN PUTASSIGNTEXT PUTSTARTUPTEXT
DELETEPARAM PUTASSIGNVALUE