Patching Applications without downtime

The major problem we have is very simple described. We want to patch an application without downtime.

Introducing a new minorversion is no problem, but fixing an existing (microversionchange) one without downtime is not possible at the moment (as I see it). Unfortunately this is very important, because we don't want to have downtimes in production. The applicaiton allways has to run. And waiting to a mentenance window is not possible.

Here is and extended scenario now:

Environment: 2 Cics Regions (Region A, Region B) below a platform hosting the same application.
Language: It should not matter if java or pli
Entrypoint: hostname/application/majorversion/minorversion
Old Applicaiton: app1, Version 1.0.0 - State is enabled and available
New Application: app1, Version 1.0.1 State is defined
Requirement: Switching to the new Applicaiton as soon as all transactions on the old end.

A scenario to enable the new application could be as followed:

-> As soon as you move the new application to availabe state, Cics should finish all running transactions in Region A.
-> Then cics should make the entrypoint of the application unavailbale in Region A and all the work for this application should now only go to Region B.
-> Next the new application should be made available in Region A.
-> Now Region A is hosting the new application. This is the time when Cics should switch hosting the applications only on Region A.
-> Cics now should switch all transactions for the application to Region A and start upgrading the Applicaiton in Region B.
-> If this is finished both Regions should be able to take the work again.

If there is only one cics region below I understand this can not work and of course there would be a downtime. But also with only one cics region at least a switch to the selected version with one click in cics explorer should be possible.