I don't know how you want a new handle assigned, but the following should show you how the references are meant to be done:

my_sub(\$handle);
print $handle->[0];

sub my_sub{
    my $handle = shift;

    if (handle_not_valid($$handle)) {
        $$handle = new_handle();
    }

}

sub handle_not_valid {
    return !ref(shift);
}

sub new_handle {
    my @arr = (4,5,6);
    return \@arr;
}
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