I think this is what you want:

#! perl -w

use strict;
use diagnostics;

use Carp;

sub iterFac {
    my $max = shift;
    my $val = shift || 1;
    my $cnt = shift || 1;

    Carp::cluck("we are currently here:");

    return $val if $cnt > $max;
    #iterFac($max, $val*$cnt, ++$cnt);
    @_ = ($max, $val*$cnt, ++$cnt);
    goto &iterFac;
}

my $x = iterFac(5);
print "Factorial 5 = $x\n";
[download]

Note how I've used Carp::cluck to show where we are at all times. If you remove the # from the iterFac call and comment out the @_ assignment and the goto, and run this, you'll see how it cluck's that it gets 5 subroutine calls deep. But as-is, the cluck always shows only a single subroutine deep.

I think that's what you're looking for, but someone with an actual CS degree may show me wrong ;-)