sub something {
    my( $string ) = @_;
    ## $string is a copy of the argument 
}

my $hugeString = ........;

something( $hugeString ); 

##</code><code>##

fuzzyMatch( \$hay, \$nee, 3 ); ## pass references to needle and haystack

##</code><code>##

sub fuzzyMatch {
     my( $rHay, $rNee, $misses ) = @_; ## the 'r's are to remind that these are references

##</code><code>##

     my $lNee = length $$rNee; ## read as: $lenghtNeedle = length of the data $, referenced by $rNee