# Possibly named argument syntax:
threads->create('stack' => $size,
                'code'  => 'function', # or sub{} or \&func
                'args'  => ...);

# Or using a hash ref as suggested in PBP:
threads->create( { 'stack' => $size,
                   'code'  => 'function', # or sub{} or \&func
                   'args'  => ... } );