Indeed, that sentence confused me. The OP might have meant when the function is called recursively ... Here is some code for the OP that shows how to maintain a "global" variable, but not how to share variables between runs of a script.

#!/usr/bin/perl

use strict;
use warnings;

our $outer = 5;
recurse($outer);

sub recurse {
    my $inner = shift;
    $inner--;
    return if $inner < 0;
    print "outer: $outer\ninner: $inner\n";
    recurse($inner);
}
[download]

UPDATE: You make it seem so crystal clear, holli. Oh well, here is a recursive sub in case someone needs it. :D

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)