my %argHash = (
    abcd => 'efgh',
    ijkl => 'mnop',
);

&first(\%argHash);

sub first {
    my $args = shift;

    print "$_ => $args->{$_}\n" foreach sort keys %$args;

    &second({%$args, qrst => 'uvwx'});
}

sub second {
    my $args = shift;

    print "$_ => $args->{$_}\n" foreach sort keys %$args;
}