What is a PCB Mask?

[LalitaForums]

Hi,

Can you please explian me what is a PCB mask? I have read through the manuals but I do not get it. Can there be a simple explnation about it?

Is not it just same as PCB?

[Anuj Dhawan]

Hi LalitaForums,

No - it is not same as PCB. After all "mask" must have been added for some purpose!

Every (COBOL-IMS) program will have its own PSB known as 'Program Specification Block'. The PSB used by a program will contain one or more PCBs. For a program to communicate to the database, program talks to PSB ( as PSBs are stored externally to the application program) and in turn, talks to the database. In doing so, program needs a communication with PCBs in the PSB - which is done using PCB Masks.

The PCB mask holds IMS interface details like this:

Code: Select all

Database Name			    Char 8
Hierarchical Level		  Char 2
DLI Status Code			  Char 2
Processing Options		  Char 4
Reserved for DL/1		   Binary 4
Segment Name Feedback     Char 8
Feedback Key Length		 Binary 4
Number of Sensitive		 Binary 4
Segments
Key Feedback Area		   Char n

Hope this helps.