Activating and checking the SOAP Log

I'd like to access and view the soap log. Apparently there is a global for that (^ISCSOAP) (http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...), but insofar I have been unsuccessful finding the exact cache command for viewing the soap log or changing it so that it logs both incoming and outgoing traffic. Can anyone enlighten me?

I.e. I am trying stuff like:

set ^ISCSOAP("Log") = io   

write ^ISCSOAP("Log)

but those don't work.