ILE C question. Access to System Heap instead of Fast Heap

["Smith, Graham (EBM)" <Graham_SmithEBM@xxxxxxxxxxx>]

Hi all,

Its my first posting to this list so treat me gently!

We're using ILE C based programs to interface with IBM's MQSeries product on
an AS/400 at V4R4M0 os level..

We have a requirement to receive an approx 20MB MQ Message from a queue.

To that end our program attempts to allocate (using Calloc function) a
portion of memory 20Mb in size.

The calloc fails to return a pointer which indicates that it couldn't
allocate the memory.

I notice from the ILE C manuals (C/C++ Run Time Library Reference) that ILE
'C' programs usually make use of the "Fast Heap" which has a maximum size of
16 711 600 bytes.

Its possible (allegedly) to use System heap by setting the _HEAP_SIZE macro
to _NO_DEFAULT_HEAP.  This should then give access to much more memory.

I've tried redefining _HEAP_SIZE  to _NO_DEFAULT_HEAP in my program before
the first mallco/calloc with no sucess.
I've also tried altering the STDLIB.H definition for _HEAP_SIZE from
_C_heap_size to _NO_DEFAULT_HEAP.  Equally no success.

Any suggestions would be most useful.   I cannot claim to be an experienced
'C' programmer on any platform so plain and simple english explanations
would be best.

Regards
Graham Smith
Graham_SmithEBM@Heinz.co.uk

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