Customize member MFAAS in the CNTL data set. This is the started task JCL procedure for Mainframe Access Application Servers such as Endevor, ChangeMan, and AMS. Use the ISPF change command to change HLQ to your qualifier (hlq).
If you are using IBM's TCP/IP, overtype TCPIP.OS390.TCPDATA with the name of your installation's "TCPIP.DATA" data set (tcpdata).