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Sunday, June 24, 2012

COBOL Copy-book Expansion tool XP in Rexx

Q. What is a copy-book in COBOL?
On Mainframe systems, a Copybook is a reusable code-snippet, that may be inserted into several different programs. Copybooks are separate files, generally containing COBOL variable declarations(record layouts) or procedural code(COBOL Statements like MOVE, ADD etc). For example, you may create a COBOL Copy-book A.


Now to insert this code in your program(s), you merely code the COPY statement in COBOL Program.


At compile-time, any references to these external copy-books are resolved. In other words, the COBOL compiler substitutes the copy-book code in your COBOL Program. What the COBOL compiler would do is expand this copybook inline.


If you took up the C programming course as one of your subjects, while you were in college, its easy to realise - COBOL copy-books work just like include <stdio.h> Header files statement in C.
Q. What does the copybook expansion utility XP do?
On analysing COBOL Programs, you often encounter variables in COBOL code, that aren't declared in the the program-source itself, rather in a separate external Cobol copy-book. At times, you may want to look at the definition of the variable – the PICTURE Clause, or the 88-Level values it can take. If the variable is a Group data-item, you might be interested to know its break-up, the 05- and 10- Level data-items under it.

Most COBOL Programs that run in the Production environment, typically refer to several external copy-books. Copybooks may reside in different libraries, based on your Mainframe shop standards. For large programs referring to several copy-books, an average programmer spends a good deal of time (i) navigating to the copy-book library, (ii)locating the desired copy-book, and then viewing it.

The XP Macro written by me, expands the COBOL copy-books in a program in-line, by searching them in user-specified libraries.
Q. Sounds interesting, but what are the features of this product? Does it have any limitations?
1. Currently, I have added support for upto 5 user-specified libraries.
2. The XP Macro properly ignores comment-lines. A commented COPY Statement will not be expanded.
3. Shows the copy-book expansion progress in real-time.
4. It has been tested with the version-management tool Changeman.

1. Does not support the REPLACING ALL option of the COPY Statement yet.
2. No checking in place, to ensure if the user-specified library is valid. I am working on this.
Q. How do I use the Cobol copybook expansion tool XP?

1. Open your COBOL Program in the ISPF Editor.


2. Type XP on the Command line in the ISPF Editor.


3. Enter the copy-book library, you would like to search in, for the copy-books.


4. Pause while all the copy-books are expanded, and wait for it to complete.


5. The expanded output appears like this -


Q. How do I install XP Utility at my Mainframe shop?
To install and use the XP utility, you need to copy over the Rexx Source-code and the panels to your SYSPROC and ISPPLIB Libraries.

Rexx Source
XPPAN01 Panel

XPPAN02 Panel

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