iRule "proc" Question

I would avoid using the tcl proc to define user defined libraries.

I have not seen explicit documentation indicating that what happens with respect the Clustered Multi Processing especially if your library has any static variables.

Also your library has to be bug-free, since any error will not just affect the current connection but the overall tmm process.

My recommendation is to just use iRule snippets for what you want done on the same event and then use iRule event priorities. Ofcourse this approach may not apply to all situations.