Malcolm said:
This is a limitation built into your compiler. The real answer is to get a
different compiler.
It may be possible to write functions bigmalloc() and bigfree() in assembly
langauge to do what you want, but I suspect it won't be easy - the 256MB
limit will be there for a reason.
Anyway, 256 MB should be enough for anyone.
Actually it isn't a limitation of the compiler as such, it's the OS and
can be solved with a different compiler with the correct flags available
OR an environment variable depending on the version of AIX. That's the
problem with answering OT questions in clc with nonsense about assembly
langauge, instead of just redirecting them.
The OP should run along to comp.unix.aix and could do worse that
Googling for "maxdata" and/or "LDR_CNTRL".