RE: Re[2]: RPG on other platforms...

[<BVStone@xxxxxxxxxxxxxx>]

> -----Original Message-----
> From: Buck Calabro [SMTP:mcalabro@commsoft.net]
> Sent: Tuesday, February 24, 1998 3:36 PM
> To:   MIDRANGE-L@midrange.com
> Subject:      Re[2]: RPG on other platforms...
> 
> 
> >Jim Welsh wrote:
> >
> > I've been asked by my employer to do some research on the effects of
> > running an RPG III
> > program on platforms other than the AS400.
> >
> >As far as your information on reentrant goes: All programs on the
> AS/400 are
> >reentrant by nature.  There is no special coding required.  The
> compiler creates
> >an object which contains the instruction set and base memory offset
> to the data.
> >Each user upon calling the program will be assigned a base memory
> address for
> >their data and control information to track the current instruction
> being
> >executed.  So A + B = C turns into OffsetForA + OffsetForB =
> OffsetForC and is
> >executed as (UserBaseAddress+OffsetForA) +
> (UserBaseAddress+OffsetForB) =
> >(UserBaseAddress+OffsetForC).
> 
> Kind of an interesting way to look at the PAG, but it gets the idea
> across!
> 
> >Special coding was required for the S/36 MRT programs which were a
> crude attempt
> >at reentrant concept: one copy of instructions, many copies of data.
> 
> All too true!  
> But is Jim asking about re-entrancy or recursiveness?
> 
> Re-entry means that no matter how many people are using a program,
> only one copy is active in memory at once.  Recursiveness means that
> RPG program A can call RPG program B who can call RPG program A
> again.  That's not allowed in OPM RPG (sadly, I haven't checked for
> ILE.)
> 
[Stone, Brad V (TC)]  But for each job there would be a different copy
in memory for programs.  Display files, not so.  Right?  

> Once Program A is in the job's call stack, it can't be CALLed again
> or you'll get:
> Message ID . . . . . . :   RPG8888       Severity . . . . . . . :   99
> 
> Message type . . . . . :   Inquiry
> 
> Date sent  . . . . . . :   02/24/98      Time sent  . . . . . . :
> 15:36:19  
> 
> 
> Message . . . . :   CMD called itself recursively (C S).
> 
> Cause . . . . . :   The RPG program CMD called itself or another
> program which
>   then called program CMD.
> 
> Recovery  . . . :   Enter C to cancel, or S to obtain a system dump.
> 
> Possible choices for replying to message . . . . . . . . . . . . . . .
> :      
>   C -- Cancel
> 
>   S -- Obtain system dump
> 
> 
> Buck Calabro
> Commsoft, Albany, NY
> 
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[Stone, Brad V (TC)]  
Bradley V. Stone        
bvstone@taylorcorp.com
http://prairie.lakes.com/~bvstone/
"People train don't run out of Wicheta... Lessn' you're a hog, or a
cattle.  People train runs out of Stubville."


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