@Override
	public boolean growsNegative() {
		synchronized (function) {
			return (paramStart >= 0);
		}
	}
A stack that grows negative has local references negative and
parameter references positive.  A positive growing stack has
positive locals and negative parameters.

@return true if the stack grows in a negative direction.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/oldfunction/OldStackFrameDB.java