IMS DB/DC Tips.

[Anuj Dhawan]

1. It usually confuses that what is a Alternate PCB when we already have PCB for an IMS Transaction, if it confuses you too, please read on for a small explanation:

Alternate Program Communication Block (TP PCB) is defined by the user, that can be used to describe output message destinations other than the terminal that originated the input message. Where SAMETRM=YES is not implicitly or explicitly specified, an alternate PCBs destination can be either a logical terminal or an input transaction queue.

[Anuj Dhawan]

2. IMS runs as a sub-system under zOS. DFSRRC00 is known as IMS or universal region controller or IMS in Batch.

DFSRRC00 is controlled using a number of parameters.These Parameters differ depending from the execution environment (BMP, DBB, JMP, ...). The symbols in the JCL might be different at different sites, but the meaning remains the same.

[Anuj Dhawan]

3.

DL/I (Data Language/I) is the language used to manipulate IMS databases. You can either access DL/I directly, through the Call-Level Interface (Call 'CBLTDLI') or indirectly, via the High Level Interface (EXEC DL/I).

With the Call-Level Interface your program calls the DL/I program, CBLTDLI, to access and/or manipulate IMS databases. The value of the parameters passed informs 'CBTDLI' as to what action the Programmer wishes it to perform.

In the High-Level interface, instructions are given via EXEC DL/I commands. These commands are converted to calls to the High Level Programming Interface via a pre-processor. The High Level Interface was developed subsequent to the Call Level Interface as a way of simplifying the DL/I interface for IMS programmers. Because of this, it has become the preferred way of accessing IMS databases.

[Anjali Chopra]

Tips on IMS DB are nice to see they are rare on web to search.

Appreciate your efforts Anuj!

[Anuj Dhawan]

Thanks for the feedback! They give you the needed moral boost - appreciate it!

Regards,