The user-stream post-hook is, if defined, called after all the streams have been defined, once for each of the three standard streams. It has a slightly different prototype:
void user_stream_post_hook(int which, SP_stream *str)
str is a pointer to the corresponding
structure. There are no requirements as to what this hook must do;
the default behavior is to do nothing at all.
The post-hook is intended to be used to do things that may require that all streams have been created.