Rather than generating them all up front (which would be pretty silly if you don't wind up using them all), why don't you generate them one by one as you need them? A closure-as-iterator would work pretty well:

#! /usr/bin/perl -w

use strict;

sub make_gen {
    my $num = shift;
    sub { sprintf '%09s', $num++ }
};

my $g1 = make_gen( 1 );
print $g1->(), "\n", $g1->(), "\n\n";

my $g2 = make_gen( 'zzx' );
print $g2->(), "\n" for 1..4;

__END__
output:
000000001
000000002

000000zzx
000000zzy
000000zzz
00000aaaa
[download]

You can play around with what the internal sub returns, in order to generate the appropriate codes for your application.

update: fixed length of codes: was 10 instead of 9. I could never read a spec :o)