PCB= parameter for procedures

Use the PCB= parameter in procedure to specify the size of the dependent region interregion communication area (DIRCA); the size specified must be a 3-digit number (for example, 001) representing the number of 1 KB blocks of subpool 251 to be reserved to hold a copy of your PCBs.

If you do not specify a DIRCA size or if you specify a size of 000, IMS uses the system default for this message region. The size of the system default, determined during system initialization, is the maximum size required for any PSB. If necessary, this system default is updated when an online change is made or when a dynamic PSB is scheduled.

If you specify this parameter, the specified size is always used. If the size required is larger than the specified size, the region abends with a user 0242 abend code.

Normally, you should not specify this parameter. You can use it to reduce the DIRCA size for a region when PSBs with small DIRCA requirements are scheduled into this region.

The output from message DFS589I occurring during ACBGEN facilitates DIRCA size calculation. Each PSB has a PCB= value that is the sum of the PCBs within it. The PCB value + 64 becomes the required DIRCA in bytes.