Kickstart on s390x fails with "No method given for cmdline mode, aborting"

Issue

•      When trying to kickstart a new guest under z/VM the kickstart fails with "No method given for cmdline mode, aborting".
•     The kickstart file in question was generated by a normal install of RHEL6 under z/VM.

•      The parameters file has the following entries.

    root=/dev/ram0 ro ip=off ramdisk_size=40000
    CMSDASD=191 CMSCONFFILE=RHEL6.CON
  ks=http://<kickstart-url>  
    RUNKS=1 cmdline