Mainframe, MVS and zOS Discussion

Hi,

There was this basic sounding question - but it makes me understand that it's tough to explain it in plain English to someone about how's IMS DB and DC works?

I said that there is DBDs, PSBs and PCBs which connects all together to make the application work. The interviewer was convinced though I think there can be better explanation too, can someone please provide me a direction.

Regards,

Let's talk about IMS DB - DFSRRC00 is 'IMS in batch'. DFSRRC00 invokes the 'COBOL program' like it were a sub-module but without any knowledge about parameters to be passed to that module - what the parameters do to the program is a separate thing.

IMS DB loads the DBD and the PCB Control-Blocks into Memory. These PCBs, are referenced by the COBOL program in Linkage Section by the PCB Mask and in Procedure Division. COBOL program get the address of the DBD and the PCB Control Blocks this way.

Thank you Anuj. This is very to the point and crisp explanation and helps.

Regards,
E377878