How is the default java heap size determined? - Stack Overflow

You can use the following command to find out the defaults on the system where your applications runs.

java -XX:+PrintFlagsFinal -version

Look for the options MaxHeapSize (for -Xmx) and InitialHeapSize for -Xms.

On a Unix/Linux system, you can do

java -XX:+PrintFlagsFinal -version | grep HeapSize

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