I don't think it's an official Microsoft SP?
If that is the case, I can't use it
Not Invented Here!
Correct, sp_WhoIsActive is a very comprehensive work by SQL Server MVP Adam Machanic. And if you have a policy that you must write all queries and not use third-party software, free or paid for, the manager who invented that policy should be fired. You are wasting time by writing something that people has already implemented, and the risk is that you walk into the same traps as they did.
Erland Sommarskog, SQL Server MVP, www.sommarskog.se