The stack floor is a system-defined address below which the stack cannot grow. All programs in the system must avoid accessing locations in the stack segment that are below the stack floor.
Other system invariants related to the stack must be maintained by all compilers and assemblers:
Interlanguage Calling Conventions
Corresponding Data Types
Using the Subroutine Linkage Conventions
in Interlanguage Calls
Sample Program: C Calling Fortran