I've searched a little bit on maximum 32 bit heap sizes per application and it seems the 1.6GB heap size limitation is caused by Windows. For example, here is a small explanation by Oracle:
Why can't I get a larger heap with the 32-bit JVM?
The maximum theoretical heap limit for the 32-bit JVM is 4G. Due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead, in practice the limit can be much lower. On most modern 32-bit Windows systems the maximum heap size will range from 1.4G to 1.6G. On 32-bit Solaris kernels the address space is limited to 2G. On 64-bit operating systems running the 32-bit VM, the max heap size can be higher, approaching 4G on many Solaris systems.
As of Java SE 6, the Windows /3GB boot.ini feature is not supported.
If your application requires a very large heap you should use a 64-bit VM on a version of the operating system that supports 64-bit applications. See Java SE Supported System Configurations for details.
2GB should be possible if Gamestudio is ported to Solaris.
I would suggest not to come even close to 1.6GB. On some Windows systems this might work while on others 1.4GB could be to much.
