If all works fine on Db2 v12 M509 (ie without new func mode), then all will still be fine to apply the new func mode to Db2 v12 and no need to re-BIND Gen DBRMs.
Part of the conversion to M510 is a job that checks when packages being used were last BOUND and against which version of Db2.
Assuming this has been done, this re-BIND to use Db2 v12, within the required time, another re-BIND is not needed.
This is documented in the Db2 guide: https://www.ibm.com/docs/en/db2-for-zos/12?topic=d1fl-function-level-510-activation-enabled-by-apar-ph33727-april-2021
For PTFs, please see this Community Announcement. Let me reference this CA GEN Community Announcement for you, which references PTFs for Db2 v12:
You can find the solution here:
- Gen's Mainframe Solution Downloads
- Select your Gen 8.6 product.
- See "UPGRADE C, C++, COBOL AND DB2 FOR GENERATORS AND RUNTIMES" for LU01883, LU01884, LU01885, LU01886, LU01887, LU01888, LU01889, and LU01908.
These PTFs are to deliver re-compiled Gen code that can run in either Db2 v12 or Db2 v11 at v11r1m510. These PTFs do NOT provide fixes required to enable Gen to run on Db2 v12. Gen without these PTFs can run on Db2 v12. Gen with these PTFs cannot run on Db2 v10 or Db2 v11R1M509.
Db2 v12 new func can be applied regardless of applying the Gen Upgrade PTFs.