Re: Limits on some object sizes <= 16M

[Jim Langston <jimlangston@xxxxxxxxxxxxxxxx>]

I'm updating some S/36 programs to RPG IV, which means changing the 3 byte
pointer to 4 byte.  Incidentally, 3 bytes is 0 to 16776215.  So, obviously the
space pointer is a 3 byte pointer, ala S36 days.

To convert my program from S36 to RPG IV I have to change the size of the
pointer so I get the correct data.  It seems to me that if IBM were to go 
back and make the pointer into the space 4 bytes (4g) or terabyte size (not
sure how many bytes that is, my calculator won't go up that far) then a lot
of programs would have to be changed to use these new pointers, perhaps breaking
a lot of user programs.

So, what are the system architecture elements that restrict the size of the
space?  My guess, none whatsoever.  So why doesn't IBM do it?  Because they 
don't
want to break their customers programs, but instead give us other memory areas
we can work with (teraspace) instead.

Regards,

Jim Langston

Me transmitte sursum, Caledoni!

Steve Richter wrote:
> 
> >
> >Well, that's all for now. I would like to see this whole "thread" or topic
> >put to rest.  So, what's the "big deal"?
> >
> 
> mark,
> 
> The question is: what are the system architecture elements that restrict the
> size of the space and enable the teraspace and mmap of a stream file?
> So far, the question has not been answered. If the question cannot be
> answered, than I agree it should be put to rest, otherwise I would like it
> to stay awake.
> 
> steve richter
> 
> ps: if ibm is proud of the way they implemented the mmap and teraspace,
> wouldn't they want to publicize it?
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