Version 11 of our favorite DBMS was made generally available way back on October 25, 2013 and IBM has not been marketing and selling this version since July of 2018. But if you are still using Db2 11 IBM has continued to provide support... and will continue for the first three quarters of 2020. But after that, support ends.
In other words, the end of support date for Db2 11 for z/OS is September 30, 2020. And that date appears to be a firm one... don't bet on IBM extending it.
Whtat does that mean for you if you are still using Version 11? It should mean that you will be spending the first three quarters of 2020 planning for, and migrating to Db2 12 for z/OS.
There are a lot of great resources that IBM provides to help you migrate smoothly. Here are a few of them for you reference:
Db2 12 Installation and Migration Guide
Db2 12 for z/OS Product Documentation
Webcast: Db2 12 for z/OS Migration Planning and Customer Experiences with John Campbell
Db2 12 for z/OS Migration Considerations (Mark Rader)
So if you are still running Db2 11 and you haven't started planning to upgrade, now is the time to start planning... and if you have started planning, that is great, because 2020 is the time to get your shop migrated to Db2 12!