What is the difference between -Xss and -XX:ThreadStackSize?

Question

I just want to control the stack size for all of my threads in a Java (groovy) application. For the Hotspot Oracle VM, I know that there are two parameters doing that (-Xss and

Answer 1

The Oracle Java SE 8 docs suggest that -Xss and -XX:ThreadStackSize=size are equivalent. However this not correct. Try eg.

java -XX:ThreadStackSize=1024 -version
java version "1.8.0_171"
Java(TM) SE Runtime Environment (build 1.8.0_171-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b11, mixed mode)

java -Xss1024 -version
The stack size specified is too small, Specify at least 160k
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

This is fixed e.g. in the Java 14 documentation:

-XX:ThreadStackSize=size Sets the Java thread stack size (in kilobytes). Use of a scaling suffix, such as k, results in the scaling of the kilobytes value so that -XX:ThreadStackSize=1k sets the Java thread stack size to 1024*1024 bytes or 1 megabyte.

and

-Xss size Sets the thread stack size (in bytes).