IMS DB 4 Top Program Control Blocks

In IMSDB- PCB has a key role. Because this acts as the program’s interface to the database. I-O PCB is the first one we need to give in the Entry statement of a program.

There are 4 PCBs available:

  • I-O- PCB: It will do DBCTL requests. If the program not using the IO PCB, so, no need to be defined in PSB generation. If the program is using IMSDC, so we need to define IO PCB in PSB generation.
  • GSAM PCB: A PCB defines for GSAM applications. It is called GSAM PCB. TYPE=GSAM.
  • Alternate PCB: If we want to divert the program flow to the other terminal, we use alternate PCB instead of I-O PCB.
  • DB PCB: It is the program’s interface to the database. Each database view one PCB is required. It can be a full-function PCB or DEDB PCB.


Author: Srini

Experienced software developer. Skills in Development, Coding, Testing and Debugging. Good Data analytic skills (Data Warehousing and BI). Also skills in Mainframe.

2 thoughts

  1. Hi Srini…could you please help me in providing some reference material for IMS…I don’t know anything about IMS..


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