my $default= {
    stackBytes => 4*1024,
    ...,
};

sub getDefault {
    return $default;
}

sub new {
    my $us= shift @_;
    my $opts= shift @_;
    if(  $opts  &&  ! isa($opts,"HASH")  ) {
        $opts= {
            code => $opts,
            args => \@_,
        };
    }
    my $class= ref($us) || $us;
    my $proto= ref($us) ? $us : $class->getDefault();
    my $self= bless { }, $class;
    my @configKeys= keys %{ $class->getDefault() };
    # add error checking to taste here,
    # but this conveys the idea
    @$self{ @configKeys }= @$proto{ @configKeys };
    @$self{ keys %$opts }= values %$opts;
    return $self;
}

##</code><code>##

my $threads= threads->new( {
    stackBytes => 16*1024,  # default
    ...
} );
...
my $worker= $threads->create( ... );
my $deep= $threads->create(
    { stackBytes => 32*1024 },
    ...,
);
$threads->setStackBytes( ... );
my @hive= map $threads->create( ... ), ...;

##</code><code>##

my $threadFactory= use threads;

##</code><code>##

require threads;
...
    my $child= threads->create( \&mySsub );

##</code><code>##

require threads;
my $threads= threads->new( {
    stackBytes => ...,
} );

##</code><code>##

use threads(
    Factory => \my $threads,
    StackBytes => ...,
);