On Thu, 10 May 2018 15:29:15 +0000, Seymour J Metz <[email protected]> wrote:

> If it's bimodal than it's not running under
> OS/VS2 3.8 (MVS).

Confusion in terms again.

By "bimodal" I mean "capable of being run
as *either* AM24 or AM31".

So yes, a bimodal 32-bit module, like the ones
I create, run just fine under MVS 3.8j running
on standard S/370 hardware. Of course they
are limited to 16 MiB of memory when run in
such an environment. But take the bimodal
(actually trimodal) load module to MVS/XA
and suddenly you get 2 GiB of memory
available. What I am asking for is for z/OS to
up that limit for trimodal 32-bit modules to 4 GiB.

> If it's bimodal and it is running into memory
> constraints, trimodal is only a bandaid; it needs
> a rewrite as AMODE64.

Needs a rewrite as a 64-bit module using 64-bit
registers with 64-bit addressing. Yes, it depends
on the specific application. If an extra whopping
2 GiB saves the day, you don't need the overhead
of 64-bit registers.

> The question isn't whether AMOD24 behavior
> can be dispensed with; it's tracking down all of
> the existing code that has to be changed.

If you find that your AMODE24 application is
starting to break the 16 MiB limit, then my
suggestion is that you track down those
references and make your application not
just bimodal, but trimodal, in preparation
for one day having accessing to 4 GiB of
memory instead of just 2 GiB.

> How many people are changing memory constrained
> AMOD24 code to AMODE31 these days, rather than
> rewriting it as AMODE64? How many errors will get
> introduced in the process?

I have no idea how many people are simply
making their code bimodal instead of
creating 64-bit applications. As far as I know
it is unusual to switch to 64-bit applications.
Regardless, I am actually interested more in
compilers changing to start producing trimodal
32-bit load modules, or unimodal 64-bit load
modules, as a user option.

BFN. Paul.

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