The recitation should have the purpose of
(i) Solving illustrative problems
(ii) Resolving conceptual problems that students may have related to the
lectures
(iii) Explaining in detail any issues that students may have with
solutions of already submitted homeworks-
i.e. illustrate the methodology used, alternates solutions available
etc.
(iv) provide clarifications for homeworks assigned--though care should
be taken to
provide this uniformly.

The recitations should be required. Typically I don't use attendance in
the grade but it should be left to the instuctor.