The f$S+g directive tells the compiler to generate stack checking code. This generates code to check if a stack over ow occurred, i.e. to see whether the stack has grown beyond its maximally allowed size. If the stack grows beyond the maximum size, then a run-time error is generated, and the program will exit with exit code 202.
Specifying f$S-g will turn generation of stack-checking code o .
The command-line compiler switch -Ct has the same e ect as the f$S+g directive.
By default, no stack checking is performed.