Haven't heard about any certification for CICS or COBOL. There are several courses where you can get a badge though. Below are 2 courses which are available for free:
For Db2 on z/OS, IBM have some certifications exam. For Db2 12, there's the DBA Fundamentals and Administrator exam. There are also other exams for Db2 11 that are still available.
For Db2 on LUW, IDUG offers 2 exams (Foundations and Administration), but you will need to be a member to purchase the exam.