Program Control Blocks, IO

AMB generates an IO PCB to define a program control block.
Restriction: This topic applies only when the AppMaster Builder AddPack has been installed, and applies only to Windows platforms.


  • IMS
  • IMS/SQL mixed target

Linkage Section:

The IO PCB AMB generates has the following format in the Linkage Section:

01  IO-PCB.
    05  IO-PCB-LTERM        PIC X(8).
    05  FILLER              PIC X(2).
    05  IO-PCB-STATUS       PIC X(2).
        10  IO-PCB-DATE     PIC S9(7) COMP-3.
        10  IO-PCB-TIME     PIC S9(7) COMP-3.
        10  IO-PCB-MSG-SEQ  PIC S9(7) COMP.
    05  IO-PCB-MOD-NAME     PIC X(8).
    05  IO-PCB-USER-ID      PIC X(8).


  • In a AMB IMS/SQL program, code a PSB with the same name as your DB2 subschema. The PSB must specify an IO PCB (by setting CMPAT=YES in the PSBGEN). If your program uses MSG-SW, the PSB must also specify an alternate IO PCB.
  • A program requires IO PCBs to obtain an input message and return a reply to the originating terminal.
  • To send a message to a logical terminal instead of to the originating terminal, code the MSG-SW call and specify an alternate IO PCB that you define with MODIFY=YES in the program specification block (PSB). MSG-SW cannot include the EXPRESS keyword when it references this alternate IO PCB.