IN PS 5C the option is hidden in the little dropdown caret in the right upper corner of the timeline container. if you click on that, you get a list of options, one of them is 'document settings...' There you can set the duration, frame rate and fps. I believe this is also there on the later editions.
in the same dropdown you find a lot of other timeline related options, which you would normally expect to be on the timeline layers it self, for example with right clicking the layer on the timeline. Why they did it this way, i have no clue but i expect it to be patent related.