Re: Record size limitation in RPG - MQ Series

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxxxxxxxxxxxx>]

To add to the confusion (!!) -- user spaces have been described as similar 
in function to data areas, in that they are an unformatted space (type 19) 
that can be used as the will of a developer. We see the object-based nature 
of the 400 here - both objects are object type 19 - a "space" - with 
different subtypes. They both have the common characteristics of a space, 
with differences, depending which subtype they are. E.g., a data area has a 
size limit that a user space does not. A user space has no additional tpe 
attribute (*CHAR, *DEC), whereas a data area does.

BTW, a physical file is a type 19 subtype 01. There are about 130 objects 
of type 19, with different subtypes. Some are object types we can see - 57 
of them, including *LIB, *TBL, *FILE - all kinds of things. The rest are 
objects we can't manipulate from XPF (above MI) - a mail document is in 
this group, e.g.

To be practical -- user spaces have on great asset,aas jt said - they can 
extend automagically, if you change one of their attributes to this 
setting. This means that, instead of allocating memory yourself, with all 
its concomitant dangers, you just refer to a location in the user space, 
and the system makes it big enough to include that address. The maximum 
size is, in fact, 512 bytes less than 16 megabytes - someone else knows 
exactly what is in those 512s.

Another interesting bit, first mentioned in MidrangeServer, I think, is 
that you can view and change user spaces by using the DSPF and EDTF 
commands. EDTF is meaningful only with text data - it won't show you binary 
data, and has no way to show the hex form, as DSPF does (F10). But tres 
cool! You can even CPY a user space to a PF (has to exist before copying) 
or a STMF. There is another possibility which I leave as an exercise for 
the reader.

HTH
Vern

At 09:22 PM 3/20/2004 -0600, you wrote:
> Data areas (type 19 subtype 0A) and user spaces (type 19 subtype 34) are 
> two different object types.
>
> The maximum length of a data area is 2,000 characters or, if decimal, 24 
> digits with 9 decimal positions.  As of V5R2, a user space can be up to 
> 16,776,704 bytes in size.
>
> Mel Rothman
> Mel Rothman, Inc.
>
> jt wrote:
> > Hey, Carl..
> > A UsrSpc is the same thing as a DtaAra, but created with APIs....