During a VMF extend I'm getting the following message :
CAT6519E Re-add CAIVMFI and TAPEDB DDs failed on LPAR xSYS.
We have been able to finally recreate this after many many VMF extends. We are attempting to deallocate DD's TAPEDB,CAIVMFI and CAIVMFXI. During this process, one of the files is still open and we receive a Dynamic Allocation error. I have seen the error on both the CAIVMFI and CAIVMFXI. I believe this is a timing issue on when the file is actually closed and our attempt to deallocate the DD. Solution ST07703 will resolve the problem you reported with the VMF extend. Once applied, you will need to bring down the CTS address space and bring it back up. If you do not have a steplib dd in the CTS proc, then also refresh LLA before recycling CTS.