Specifying an alternate nucleus

Another less common way to change the system at an IPL is to cause the IPL program to read a member of a nucleus data set that is different from IEANUC01, the default nucleus member. One reason for such a nucleus switch may be the need to apply a PTF to the nucleus. You can IPL a secondary (alternate) nucleus by either of the following methods:
Note: When you specify an alternate nucleus, the proper architectural extension of the nucleus must also exist. See ARCHLVL for more information about architectural extensions to the nucleus.