It is beyond my expertise to answer your original (and interesting) question, nonetheless, I thought you and fellow monks might be interested in my bit of (research). I did an investigation on my system (using the ~0 >> 1 construct for integer type maximum number and working my way up using this number). Due to the dynamical typing of perl, integer numbers can go way beyond this maximum (usually that one finds in C).

#!/usr/bin/perl

use strict;
use warnings;

my $n;
$n = ~0 >> 1;
print "$n\n";
my $x = 999999999999999;
print "$x\n";
$x = 1000000000000000;
print "$x\n";
my $z = 1.79769313486231e+308;
print "$z\n";
$z = 1.79769313486232e+308;
print "$z\n";
[download]

The output:

2147483647
999999999999999
1e+15
1.79769313486231e+308
inf
[download]

There is also another older node regarding a similar issue here: http://www.perlmonks.org/?node=657332 with an insightful summary by ysth at the end. Hope this helps.