Java application to use maximum available memory in the system

There are -Xmx and max-heap-size (jnlp) options to set maximum memory java application can use.
If these options are not specified application is permitted to use only small amount of available phisical memory in the system.
That is the reason people play with -Xmx to allow application to use more memory. But this is really a nightmare as for me because there could be different amont of memory on client machine and even OS should be taken into consideration.

Is there any way to alow java application to use maximum available memory in the system?

Thanks.

-XX:DefaultMaxRAMFraction=1

• JDK-4408373 : Can we eliminate the -Xmx max heap "glass ceiling"?
• Sun's 1.5 JVM: the -XX:DefaultMaxRAM option and its cousins
• Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning - Default Heap Size

Doesn't work for web start.