I can't say how it would work on win32, but on linux, I've had luck with Perl releasing huge memory back to the system, if the array was in a thread, and the thread was joined/finished.

#!/usr/bin/perl
use threads;
use threads::shared;
use warnings;
use strict;

print $$,"\n";  # top -p $$ to check

my $alive:shared = 0;

my $thr = threads->create(\&display);

print "check mem use, then hit any key\n";
<>; #check mem use

$alive = 1;
$thr->join;

print "check mem use, then hit any key\n";
<>; #check mem use

$alive = 0;
my $thr1 = threads->create(\&display);

print "check mem use, then hit any key\n";
<>; #check mem use

$alive = 1;
$thr1->join;

print "check mem use, then hit any key to finally exit\n";
<>; #check mem use



sub display {
 my @array;
 foreach (1..10000000){
   push @array, 'aaaa';
  }  

while(1){
    last if $alive;
    sleep 1;
  }
undef @array;
return;
}
[download]