This article would benefit from an introduction that lays out the structure of what is to come. I'm expecting an article on effect systems, but it jumps straight into a chunky section on the implementation of function calls. I'm immediately wondering why this is here, and what is has to do with effect systems.

Also, this is a very operational description: how it works. It's also possible to give a denotational description: what it means. Having both is very useful. I find that people tend to start with the operational and then move to the denotational.