What's the default heap size for IBM's J9VM?

I have IBM's J9 VM (build 2.3, J2RE 1.5.0 IBM J9 2.3) installed. After getting开发者_运维百科 an OOM, the size of the heap dump is 383MB. How much heap does the JVM have?

The reason why I ask is that a 400MB heap dump seems a bit much for the default 64MB heap that I expect but I didn't specify any -Xm options. Does J9 use a different default heap size? If so, how can I find out what it is?

To print the current values, use:

java -verbose:sizes -version

According to the documentation, the default minimum and maximum heap sizes are platform-dependent. On most platforms, default -Xms is 4M. Default -Xmx for Linux is "Half the real memory with a minimum of 16 MB and a maximum of 512 MB", and for Windows, it's "Half the real memory with a minimum of 16 MB and a maximum of 2 GB".