The CA 1 FAILSAFE USERMOD is defined in PROGnn member with EXIT ADD EN(OCE_VOLUMEMOUNT) MOD(IFG019VM) as described in the CA 1 Documentation. However at IPL the exit is not activated and the following messages are issued:
CSV424I ERROR IN PARMLIB MEMBER=PROG0U ON LINE 35: 749 MODULE IFG019VM WAS NOT ADDED TO EXIT OCE_VOLUMEMOUNT. MODULE ALREADY EXISTS IEE252I MEMBER PROGPU FOUND IN SYS1.RBSG.PARMLIB
Release: Component: 1
Be sure the EXIT ADD EN(OCE_VOLUMEMOUNT) MOD(IFG019VM) statement is in a PROGxx member which is defined in IEASYSnn, which is processed before the IBM default exit is installed. If that is not the case and the PROGxx member is activated using SET PROG=XX later in the IPL process, this might be too late resulting in the error message above.
As per IBM documentation: "Controlling the volume mount exit routine through the dynamic exits facility" https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.3.0/com.ibm.zos.v2r3.idac700/oce_vm.htm
The system attempts to add exit routine OCE_VOLUMEMOUNT, unless an exit routine has been associated with OCE_VOLUMEMOUNT by PROGxx or SETPROG. If you have associated exit routines with OCE_VOLUMEMOUNT the system does not use the default exit routine. In this case, if you require an exit routine of the default name, you must explicitly add the default exit routine to PROGxx.