Mainframe application development is constantly going through changes, but the tools that support them, like the legacy library managers, are stuck two decades back. There is a need to rethink the entire lifecycle of mainframe application development process in the new CI-CD world. This is not just about plugging tools of the new world. Tools help, but the real change is in the processes and the culture.
Dennis Behm & Nicolas Dangeville from IBM has written the whitepaper linked below on the packaging and deployment strategies of the modern mainframe software development. If you are thinking about modernizing your mainframe development, I would strongly recommend you read through this whitepaper. The whitepaper covers defining the scope in a git repository. It introduces artifact repositories for mainframe, packaging mainframe artifacts, and storing them in artifact repos and then in detail about deployment managers.
I had an opportunity to be one of the reviewers of the whitepaper from UrbanCode Deploy (UCD) perspective. Whatever the whitepaper says in terms of a deployment manager, they are possible today in UrbanCode Deploy. UCD now has the ability to store / deploy from external artifact repos other than codestation. We support the new packaging explained in the whitepaper. In near future, we will be supporting YAML as the package manifest format. UCD also understands the need for full and incremental deploys (and it is the only modern deployment tool in the market that does that).