use feature qw( :5.10 );

sub uncalled_sub {
    state $huge = huge_data_structure();
    return;
}

print 'mem usage: ', my_mem(), "\n";

sub huge_data_structure {
    return [ ( 'x' x 1_000 ) x 100_000 ];
}
sub my_mem {
    my ($proc_info)
        = grep { $_->[2] == $$ } map { [ split ] } `ps l | tail -n +2`;
    return $proc_info->[6];
}
__END__
mem usage: 11220