Changing javac default initial heap size

[Wade Hennessey]

The default initial heap size in OpenJDK9 is 8m (-Xms8m), and I'd like to
increase it, but I can't find how this is specified in the build process.
It seams that most/all java binaries are based on the same main.c program
that launches a specific binary such as javac by passing it parameters
through some sort of "Launcher" that specifes the command line options.
Unfortunately  I don't understand how this is specified when javac is
linked.  -wade