Coding the checkpoint PCB mask
An application program uses the checkpoint PCB mask to check the status code that AR/CTL returns to report the results of checkpoint, restart, or rollback processing. The checkpoint PCB mask contains the same fields in the same order as defined in the checkpoint PCB.
The checkpoint PCB mask is compatible with the IMS I/O PCB mask. The only significant field for an IMS compatible program is the two-character status code, which is located at offset 10.
The following table describes the fields in the checkpoint PCB mask.
Checkpoint PCB mask fields
Field | Length(bytes) | Offset(bytes) | Description |
|---|---|---|---|
reserved | 10 | 0 | retained for compatibility with IMS |
status code | 2 | 10 | describes the results of the call AR/CTL places a status code in this field after each call. The application program should check the status code to determine whether the call was successful. |
reserved | 28 | 12 | retained for compatibility with IMS |
Define the checkpoint PCB mask as a level 01 linkage section entry. The following example shows a checkpoint PCB mask in COBOL:
...
01 CHKPPCB.
02 FILLER PICTURE X(10).
02 CHKP-STATUS PICTURE XX.
02 FILLER PICTURE X(28).