Summary

The launcher should round up the stack size specified with the -Xss option to a multiple of the system page size as required by the operating system.

Problem

The Java launcher use pthread_attr_setstacksize to set the stack size of the initial thread on POSIX systems. On some systems, like MacOS, the stack size is required to be a multiple of the system page size; otherwise, the call will fail and lead to use of the default stack size.

Solution

The launcher will try to set the stack size with the specified value. In case that fails, the launcher will round up the specified stack size to a multiple of the system page size and try again.

Specification

java -X says about -Xss option:

-Xss<size>        set java thread stack size

will be changed to

-Xss<size>        set java thread stack size
                  The actual size may be rounded up to a multiple of the system
                  page size as required by the operating system.