Re: Data structure overlay *next failure

On 6/19/2013 12:37 PM, Brian May wrote:

I don't think you are quite getting what *NEXT does.

In your example, I assume you are wanting the carr array to overlay c1 through c12. But that is not what you told it to do. You told it to overlay the data structure starting immediately after the last subfield defined for the structure you are overlaying. So it created the array after c12 since it is also a subfield of PF1_t. Others have already shown you the correct way to do this, which is to create a group field that the c1 - c12 fields will overlay using next. Then overlay the array over the same group field.

The point here is that *NEXT does not overlay starting after the previous overlay *NEXT. It starts after the previous subfield.

No, it starts at the next available position in the data structure.

D ds ds
D suba 1 5a
D subb 3a
D subc 2 3a
D subd 2a overlay(ds:*next)
/free
ds = '123456789';
subd = *all'd';
dsply ds;
return;

DSPLY 12345678dd

Subfield sub4 starts at position 9, after subb, not at position 4, after subc.

OVERLAY(dsname:*next) means "next available position in the data structure", which, as Jon has been saying, is the same as not specifying OVERLAY at all.

Arguably, *NEXT shouldn't even have been allowed for overlay on a data structure.