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;
}
[download]

Or, if you don't want to use hashrefs, you can do

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;
}
[download]

Note how the two use different braces at different times. Either is just fine. The second is prone to more errors in coercing the array @_ into the hash %args, but, so long as you know exactly what's going into that hash, you should be fine. Try them out and see which you prefer.

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.