#!/usr/bin/perl -w
use strict;
$| = 1;

{
    my $string;
    for ( 1 .. 100000 ) {
        $string .= ( 'x' x 1000 );
    }
    print "press enter to release";
    <>;
    
    undef $string;    
    print "undefined but still in scope of sub, hit enter\n";
    <>;
    # if the variable only goes out of scope.
    # you *need* to undef it!
}

print "ok,out of scope,  press enter to exit";
<>;