Such things are not really controlled by the applications any more, but rather the OS. You need a 64-bit OS to use all the RAM in such a machine.
Also, you cannot really tell how much VNL "uses". It USED 3 Gb before it reached the point where it asked for more than was available. But in modern applications RAM is allocated dynamically; there isn't a predefined size reserved for VNL.
However, the problem I know you are facing unfortunately isn't really solved by having a lot more memory, but is related to poor memory handling in VNL itself. The data you need to manage is much smaller than 1 Gb, but VNL 2008.10 makes several internal copies, ramping up the total RAM usage way too much. These things will be taken care properly of in the new version. And, we're working on getting GGA into that! ;-)