netiucv.cfb810 <bus ID of the IUCV device>: Connecting the IUCV device would exceed the maximum number of IUCV connections
Explanation
The connection cannot be established because the maximum number of IUCV
connections has been reached on the local z/VM guest virtual machine.
User response
Close some of the established IUCV connections on the local z/VM guest
virtual machine; then try again to establish the connection.