After upgrading to 16.1 syntax errors and U3998 abends occur on jobs invoking QUIKVSAM that executed successfully in prior releases.
There have been multiple instances where users reported this error on jobs that ran fine before upgrading to release 16.1.
In all cases the existing user program was not in compliance with the documented syntax. The prior releases simply did not catch the bad code.
Correcting to the documented syntax resolved the problem each time.
Please refer to Chapter 4 of the Release 16.1 Getting Started Manual on Upgrading from Previous Releases.