Java Heap Space - Cannot make large enough

Question

I am trying to set the Xmx parameter when starting up a program. If I set it to 1408M, the JRE starts up fine. If I set it to 1536M, I get

"Could not create the java virtual machine".  

I understand that it's trying to reserve consecutive memory space, but the machine I'm running on has 16GB of RAM and 13GB of that is currently free. The program I'm running is running out of heap space and crashing on me. Is there anything I can do to fix this?

Answer 1

Use a 64bit JVM. The 32bit JVM is limited (depending on the OS) to at most 3 GByte (on linux I have a limitation of about 1.5 GByte).

Answer 2

32-bit JVMs are limited to roughly 1.5 GB of heap space due to addressing constraints and the need for memory for other reasons. On Windows 2 GB is assigned to the process, and 0.5 is used for non-heap memory. If you can use PAE on Windows Server or possibly Linux, you can address up to 3 or 4 GB, respectively.

Otherwise use a 64-bit JVM.