Re: RPG on other platforms...

["postmaster" <shc@xxxxxxxxxxxxxxxxx>]

Hello Jim,

RPG III, RPG/400, and RPG IV only run on the AS/400.  AS/400 program objects do 
not run on other 
platforms.  The source cannot even be moved unless you take no advantage of the 
AS/400.  Other than 
some half-arsed attempts at putting a 400-like environment on PCs (why would 
you bother) every other 
RPG compiler I am aware of is a dialect of RPG II.  Ergo, no externally 
described data, no CAT, 
SUBST, CHECK, CHECKR, SELEC, etc, etc, etc.

All AS/400 programs are re-entrant -- meaning all jobs using a given program 
share the same program 
code (only one copy in main store) but have separate variable storage in the 
PAG.  No RPG program is 
recursive except RPG IV if AND ONLY IF you use the procedure support.  
Recursion is only supported 
in languages which use automatic storage.  RPG uses static storage. Automatic 
storage is allocated 
each time the program is called; static is only allocated the first time.  The 
big problem with 
making RPG recursive is not so much where you define the variables but the fact 
that the RPG logic 
cycle is present in every RPG program even if you request full-procedural 
processing for files and 
the cycle is not recursive.  The RPG compiler embeds code to detect whether a 
given program is 
already active in the job and generates an exception if it is.  So ...

        RPG III/400 is not recursive
        C is recursive
        CL is recursive -- who'd've believed that then!
        CBL is not recursive (I think)
        PL/1, FORTRAN, BASIC -- not sure
but all are re-entrant.

So to deal with your specific questions:

>1. What are all other possible platforms an RPG III program object can run on ?
        NONE - you can try to move the source but I doubt that will work 
without serious rework.

>2.  By what method does one code an RPG III program routine to be reentrant ?
        NONE - they simply are.  The system handles it all.

>What was done in the COBOL programs to make them reentrant was to define all 
>program
>variables in the Linkage Section, in RPG that would be the *ENTRY PLIST...
        Nothing to do with re-entrancy.

Regards,
Simon Coulter.

//----------------------------------------------------------
// FlyByNight Software         AS/400 Technical Specialists
// Phone: +61 3 9419 0175      Mobile: +61 3 0411 091 400
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