stxxl save and read vector from disk file

I'm struggling in trying to use the stxxl library in a way, that I cannot only store the data from their vector structure into a file but also recover it from that file in a rerun of my program.

I found out that you can construct a vector from a file ( http://ift.tt/1EUReaK ) but the class "file" only contains these functions ( http://ift.tt/1dSjz8C ) with no way (that I can see) to actually access an existing file with some given path.

Does someone who worked with this library before have an idea how to do that?

Thanks in advance