I will just offer that our AIX CMOD system is a beast. Handles everything, yet to see any contention.
Our external customer lookups have gone from 4,000 a month 10 years ago, to 3,000 a day which brought our z/OS CMOD system to its knees.
Now on AIX, it is handling 30,000 - 45,000 a day with minimal impact on the CPU.
We are migrating CMOD data from z/OS. Some report iterations take hours to retrieve, and upload in seconds to AIX.