Humm, don't forget that Perl uses a special variable @_ for the arguments. What you can't forget is that this array @_ is global, but it's elements will change for each call. So, the performance of @_ will be similar to a global variable, but will work as a stack, so, will work for multiple calls of the same sub and recursivelly.

This code will show that:

sub test1 {
  ++$_[0] ;
  print "T1 [@_]\n" ;
  test2($_[0]) ;
}

sub test2 {
  ++$_[0] ;
  print "T2 [@_]\n" ;
  test3($_[0]) ;
}

sub test3 {
  ++$_[0] ;
  print "T3 [@_]\n" ;
  print "end\n" ;
}

my $n = 10 ;
test1($n) ;
print "N: $n\n" ;
[download]

output:

T1 [11]
T2 [12]
T3 [13]
end
N: 13
[download]

And forget the use of a global variable for any type of code and start learning OO. Take a look at perlobj, perltoot, perlboot and perltooc.

For Object Orientation (OO) I use Class::HPLOO.