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Semantic edit concerning limitations of COBOL CALL statements
imported>Pjfarley3 m (Minor edits to notes.) |
imported>Pjfarley3 m (Semantic edit concerning limitations of COBOL CALL statements) |
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Note also that each subroutine is declared RECURSIVE though they do not all need it.
The subroutines each pass back a return value in their last parameter. The most recent release of the IBM Enterprise COBOL compiler (V6.4 as of the date of this contribution) does, in fact, support user-defined functions, which would make some of this implementation a little easier to write and read, but since many IBM shops are not yet up to the most recent level, this version is offered as one that will work with down-level compiler versions.
In the "two pass merge" subroutine (PTYQ2PMG), the final three lines are needed because
Note also that the subroutines call each other using "PIC X(8)" pseudonyms because the actually recursive subroutines cannot use the "same name" as both the PROGRAM-ID and as a variable name. This could be resolved by simply using "constant" calls (like <code>CALL "PTYQ2PMG" USING . . . </code> but using the pseudonyms allows each of the subroutines to also be separately compiled into an executable module and then dynamically loaded at run time. Many IBM shops will prefer that method to this purely "static" solution.
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