DS8A50 Gen10 - Disable the option to over-provision logical volumes above the physical capacity limit or extent pool limit

With the release of the Gen-10 DASD to obtain the full benefit of compression offered by the FCM (Flash Core Modules) the requirement is to use thin-provisioning (ESE / Extent Space Efficient) for all the logical volumes.  This can be a big change for some sites, where they are used to having no thin provisioning and may not be aware of the extreme risks involved in over-provisioning to the point of exhausting all the virtual capacity.

This comes with extreme risks and a scenario that GDPS HyperSwap would not protect from (in the event both machines were identical in configuration and exceeded the virtual capacity at the same time), the Mainframe hosts would grind to a halt if the volumes became read-only and write I/O failed.

Given the increase in volume sizes available (1TB for Mainframe CKD Volumes and 16TB for Open Systems FB Volumes) there is a possibility that a DSCLI command issued to configure logical volumes could exceed the physical capacity of the machine (over-provision).

A mainframe example of 255TB being consumed from an extent pool in one command:

mkckdvol -extentpool p0 -cap 11168 1182006 -sam ESE 000-0FF

This is a mainframe example - logical FB volumes could in theory allocate 4PB to an extentpool in a single command. 

Please make it possible to avoid over-provisioning entirely / or introduce a hard limit on the extentpool threshold set. A warning threshold alarm may not activate in time using the command in the example above and cause an unintentional outage if the pool is exhausted. 

The -opratiolimit 1 parameter of the mkextpool/chextpool is a good start, but it's based on a calculation of the total virtual capacity based on a compression ratio of the FCM in the extent pool. It would be nice if we could have a similar limit that basis the limit on the physical capacity of the FCM Drives in the extentpool.