I’ve just finished publishing update Z21-1505F. It implements vector register support in z/XDC. Vector registers are now saved and restored by z/XDC for both task mode and SRB mode execution.
There now is a LIST VREGS command to display the entire register set, and a LIST VRn command to display individual registers. Also you can zap them.
z/XDC is cognizant of when vector registers have and have not been activated within a thread, and z/XDC will never unintentionally activate them. (This cognizance is now also extended to AFP floating point registers. z/XDC will no longer activate them unintentionally as well.)