Re: Parm defined at DS/Array confusion

On 2024-08-15 1:17 p.m., Sam_L wrote:

Here's my take:

pgm0 is expecting and a two element array, a piece of contiguous memory that contains 4 7s 2 numbers. It receives a pointer to this memory.
...

The called program, pgm0, is only expecting 2 7s 2 numbers.

> Damtin DS
> D AMTA 1 14s 2 Dim(2)
> D AMTm2 1 7s 2
> D AMTd2 8 14s 2

It's only expecting 2 zoned(7:2) numbers. AMTA is zoned(7:2) DIM(2), AMTm2 is the same as AMTA(1), and AMTd2 is the same as AMTA(2).

So the whole thing is weird and indeed it's an accident waiting to happen. But the called program isn't accessing beyond the passed parameter for any of the callers even though one caller is passing 4 elements and one is passing 8 elements, so most of their extra elements would be ignored.

One free-form version of that data structure is:
dcl-ds amtin;
amta zoned(7:2) dim(2);
amtm2 zoned(7:2) pos(1);
amtd2 zoned(7:2) pos(8);
end-ds;

Another version is:
dcl-ds amtin;
amtm2 zoned(7:2);
amtd2 zoned(7:2);
amta zoned(7:2) dim(2) pos(1);
end-ds;