I don't understand what your problem is.

You write that you want to "parse a filetree". What do you mean exactly by that? "to parse", in my understanding, means to read a text file and turn it into an internal data structure. If that's what you mean, where does the file size limit comes into play? Perl doesn't care about cifs' limits, its strings can be arbitrarily long (as long as it fits into memory).

Or do you mean "recursively read a file tree"? If that's what you mean, the file tree already exists, so the path length can't be greater than what the file system supports, so I don't see a problem with that either.

Or is your problem something else? Please try to be more exact in your description.