It seems that someone else had a similar problem, as seen in this thread.
In that case, it seems that the dev in question was building a 32-bit application and running it under Windows installation, and that Windows apparently imposes some limitations on the amount of memory given to a single 32-bit application. To quote:
(The dev did later note that the limit may be higher under Windows 7 Professional; I don’t know whether it varies further under other versions of Windows.)
Does this perhaps apply to your case? That is, is your application 32-bit, and are you working under Windows?
If so, the question then comes back to that of why your program is using up more than the limit…