You wrote:
"You are calling a function from within a function. I seem to remember reading that that's a no-no."
As others have pointed out, this is perfectly OK. The stack size varies, as does the amount of stack used (depends upon number and type of parameters for each function, as well as local variables used in each function), so it is challenging to give a hard limit on this.
What you may be remembering is that C / C++ does not permit the DEFINITION of a function within a function.