Re: Parm limitation in RPGLE

On Tue, 30 Apr 2002, Lori Crane wrote:
>
> I have a question on RPGLE and Parameters.  Can anyone tell me if there are
> any limitations on the length of paramters.  We are trying to create
> headers(and pass them to several programs) and we have the following
> parameters.
>

This is a difficult question to answer...  It depends on what you mean.

First of all, let me make an assumption.  Since you say "(and pass them to
several programs)" I'll assume that you mean parameters passed to a program,
as opposed to parameters passed to a procedure.  This makes a difference,
since parameters passed to a procedure by value are limited by the size of
a variable you can declare in RPG.

Parameters passed to a program are passed by reference.   This means that,
behind the scenes, all that actually gets passed from one program to
another is the "address in memory" of the data.   Consequently, the length
of the actual data really doesn't matter to the parameter passing
mechanism.  The max length in that case is the max length of a variable
that you can define.

Of course, packed numbers can only be up to 16 bytes long, zoned can be up
to 30, integer can be up to 8, etc...  But I'm assuming that you're not
asking about the length of specific types, but rather tha max possible
length of anything.

Since the data is passed by reference, you can pass an address
to a block of memory that you've allocated manually, using the RPG ALLOC
op-code, the C malloc() function, or some similar mechanism.   In that
case, the maximum size of an allocation is the factor, rather than the
max size of a variable.   The max size of an allocation (at least, at the
moment) is 16776704 bytes.  (yes, that's 16mb - 1)

Whew.   That's quite a bit larger than 180 bytes. :)

So, those are RPG's maximums.   Then, you need to look at where they
are being passed _from_ to see if there's anything to take into
consideration on that end.

For example, there's the classic case of calling a program from the
command line, where the system allocates 32 bytes for your parameter,
no matter how long your program thinks it is.   But, I won't get into
gory details, since that's probably the most frequently asked question
around here, I'll just point you to the FAQ:
     http://faq.midrange.com/data/cache/70.html

I feel as though I've answered your question, but I'm not really sure
that I've helped :)