HSM improvement related to the ARCMDEXT EXIT and new parameter request

The Itau bank has 2 very large Sysplexes Bank and Cards.
The Bank environment has a heavy batch workload that relies on the HSM task. The batch processing has a lot of GDG datasets.
The Itau is using the EXIT ARCMDEXT to inform the HSM during the migration to not migrate some GDG generations, it is a very important step to avoid recalls during the batch window.
But, the problem in this scenario like the details in the case TS007360791, sometimes the migration start and the list resulted from the EXIT ARCMDEXT processing is passed to HSM after the migration start, so, sometimes when it happens the migration process some GDG generations that must be not migrated. In this situation when a critical batch job starts and need this same generation that was migrated needs to recall to continue the job, it is a bad scenario for Itau because it can delay the entire batch window.
During the case, it was not possible considering the current design a way to avoid this behavior, the IBM HSM support also suggested to use the parm "# GDG Elements on Primary", but this parm also will not avoid the migration of GDG generations and will not protect the batch from running recalls like the Itau needs.

So, this RFE is to request two new functions:

1. A way to make sure the EXIT ARCMDEXT and migration will be synchronized prior the migration starts, so, the migration will not migrate any GDG generation that was inside the list of ARCMDEXT, I mean it will make sure the migration will have the most current position from ARCMDEXT.

2. OR/AND create a new parameter for GDG datasets where we can inform the datasets or the number of GDG generation that we want to preserve on the primary disk and HSM can't migrate those generations. I mean here, the HSM will not consider the datasets included in this policy to be migrated.