#!/usr/local/bin/perl -w
use strict;
$|=1;
{
    my $string;
    for (1 .. 100000) {
        $string .= ('x' x 1000);
    }
    print "press enter to release";
    <>;
    undef $string; # note that memory does not get released
                   # if the variable only goes out of scope.
                   # you *need* to undef it!
}

print "ok, press enter to exit";
<>;