PCB summary
This section summarizes information concerning I/O PCBs and alternate PCBs in the supported environments. Read it if you intend to issue system service requests.
CICS online programs
- EXEC DLI
- The first PCB in your PCB address list always refers to the first database PCB (DB PCB) whether or not you specify the SYSSERVE keyword.
- CALL DL/I
- If you specify the IOPCB option on the PCB call, the first PCB in your PCB address list will be
the I/O PCB, followed by any alternate PCBs, followed by the DB PCBs.
If you do not specify the IOPCB option, the first PCB in your PCB address list will be the first DB PCB.
BMPs
- EXEC DLI and CALL DL/I
- The PCB list always contains the address of the I/O PCB, followed by the addresses of any alternate PCBs, followed by the addresses of the DB PCBs.
Batch programs
Alternate PCBs are always returned to batch programs irrespective of whether you have specified CMPAT=Y. The I/O PCB is returned depending on the CMPAT option, as follows:
- EXEC DLI and CALL DL/I
- If you specify CMPAT=Y, the PCB list contains the address of the I/O PCB, followed by any alternate PCBs, and then the DB PCBs.
Table 1 summarizes the I/O PCB and alternate PCB information.
| Environment | EXEC DLI: I/O PCB count included in PCB(n) | EXEC DLI: Alternate PCB count included in PCB(n) | CALL DLI: I/O PCB address returned | CALL DLI: Alternate PCB address returned |
|---|---|---|---|---|
| CICS® DBCTL: SCHD request issued without the IOPCB or SYSSERVE option | No | No | No | No |
| CICS DBCTL: SCHD request issued with the IOPCB or SYSSERVE for a CICS DBCTL request or for a function shipped request which is satisfied by a CICS system using DBCTL | No | No | Yes | Yes |
| BMP | Yes | Yes | Yes | Yes |
| Batch: CMPAT=N specified | No | Yes | No | Yes |
| Batch: CMPAT=Y specified | Yes | Yes | Yes | Yes |