Here's a little test program I built a while back to try this out. Run it in a terminal window such xterm and it will report the terminal size as you change it.

use strict;
use warnings;

use feature qw{ say };

$SIG{ WINCH } = \ &winch;

winch();

while ( 1 )
{
    sleep 200;
}

sub winch
{
    my( $rows, $cols ) = getRowsCols();
    say qq{Rows = $rows - Columns = $cols};
}

sub getRowsCols
{
    my $sttyOut = do {
       open my $sttyFH, q{-|}, qw{ /bin/stty size }
          or die qq{fork: /bin/stty size: $!\n};
       local $/;
       <$sttyFH>;
       };
    die qq{/bin/stty size: Unexpected output:  $sttyOut}
       unless $sttyOut =~ m{^(\d+)\s+(\d+)$};
    return $1, $2;
}
[download]

I hope this is helpful.