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

&first(\%argHash);

sub first {
    my %args = @_;

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

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

sub second {
    my %args = @_;

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