# this function is not recursive; it is called once
# and returns with the subroutine calls it /would have/
# made had it be implicitly recursive

sub get_sub (param1,...,paramN)
  # shift params, which are are assumed to data stucts refs
  initialize @retsubs = ()
  if terminating condition FALSE
    # create/modify params used in recursive call
    initialize new _param1 to some value;
    ...
    initialize _paramN to some value;
    loop to get set of next subs for next level of recursion
      push "sub {return get_sub(_param1,...,paramN);})" onto @retsubs;
    end loop
  endif 
  return {substack=>@retsubs,retval1=>'somevalue'};
end get_sub

# initialize call stack with first set of subs to call
my @callstack = array of subs returned by get_sub(param1,...,paramN);

# now execute the call stack until it's been exhausted
while(@callstack) {
  pop next $sub off of @callstack;
  execute sub ref, $x = $sub->();
  push subs returned by get_sub(param1,...,paramN) onto @callstack;
end while