How is the default max Java heap size determined?

Question

If I omit the -Xmxn option from the Java command line then a default value will be used. According to Java documentation

\"the default v

Answer 1

Java 8 takes more than 1/64th of your physical memory for your Xmssize (Minimum HeapSize) and less than 1/4th of your physical memory for your -Xmxsize (Maximum HeapSize).

You can check the default Java heap size by:

In Windows:

java -XX:+PrintFlagsFinal -version | findstr /i "HeapSize PermSize ThreadStackSize"

In Linux:

java -XX:+PrintFlagsFinal -version | grep -iE 'HeapSize|PermSize|ThreadStackSize'

What system configuration settings influence the default value?

The machine's physical memory & Java version.