Re: TeraSpace

On 6/25/2013 5:26 PM, Jon Paris wrote:

Simply compiling the program to use teraspace will do nothing for
you. It won't even use it. I believe that pretty much all the RPG
options are concerned with is can RPG access storage referenced via a
teraspace pointer.

The 7.1 enhancement was to allow RPG and COBOL to actually run in the teraspace storage model.

Advantages:
- no practical limit to the amount of automatic storage in a procedure or the program stack. Whether it's usually a good idea to go over the 16MB limit is a separate issue.
- ability to run in the same activation group as C or C++ that uses the very fast teraspace pointers

ILE RPG could always reference teraspace storage. It was only C and C++ that had options to disallow it. But in 6.1, everything can. OPM programs, ILE C programs compiled with TERASPACE(*NO), everything.

But it's not a trivial exercise to start running in the teraspace storage model. It usually involves a complete overhaul or at least a complete review of activation groups, since you can't have programs (including service programs) in the same activation group that are teraspace storage model and single-level storage model. So if most of your calls use *CALLER, you'd have to put everything into the teraspace storage model, or at least make them STGMDL(*INHERIT). If there's anything you call that you don't have control over so you can't change its storage model, then you can have difficulties.

As part of the teraspace enhancement, we also added the ALLOC H spec keyword for RPG so that %ALLOC etc could use teraspace storage with its much bigger limitations, even in the single-level storage model. That's usually the only part of the teraspace enhancement that I really talk about in what's-new presentations.