Mainframe: Top IMS DC Interview Questions (1 of 2)


It is IBM IMS data communication

2)How IMS DC program works?

It takes input from terminal, and IMS DC program, interacts with database/files, send back information to the terminal

3)What is a message?

Message is a unit of data passed between IMS DC programs and terminal

4)What is MPP?

It is also called message processing program. It takes input from terminal and process it, and sends back reply to terminal. This kind of program is called MPP. Message related processing is asynchronous in IMS DC.

5)What is MPP region in IMS?

Where all message processing programs reside. When message process is complete, that particular MPP region is freed. In plain terms, IMS executes and process all MPP programs.

6)What is BMP region?

For BMP program terminal response is not required. Message processing does not happen immediately. In simple terms, this is called Batch message processing. BMP programs, can access databases that are allocated to MPP programs.

7)What is control region?

It is a core region in IMS. It logs information about all terminal based activities and database activities.

8)What are the basic calls used in IMS DC program?

GU,GN,ISRT calls

9)How ISRT call works?

ISRT call will be used to send output message to terminal

10)Which PCB will be used?

The special PCB is IO-PCB. It is used for message processing.

11)Where IO-PCB should be declared in IMS DC -COBOL program?

In Linkage Section.

12)What is the role of DLI in IMS DC programs?

All request and response messages will be placed in IO-area. DLI helps processing of these messages placed in IO-area, in between terminal and IMS DC program.


Author: Srini

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