System tailoring at initialization time

Initialization-time choices that help to tailor the system can come from several sources:

• Various types of IPLs.
• Operator action, described in Operator entry of parameters.
• SYS1.PARMLIB and additional parmlib data sets are described in Description and use of the parmlib concatenation. This data set is one of the main sources of IPL-time parameters.
• Specifying an alternate nucleus or master catalog, described in Specifying an alternate nucleus and Specifying an alternate master (system) catalog.
• Specifying different master scheduler JCL, described in Understanding the master scheduler job control language, which includes information about when you might need different master scheduler JCL and how to establish the JCL you need.
• The JES2 or JES3 initialization data set. (See either z/OS JES2 Initialization and Tuning Guide or z/OS JES3 Initialization and Tuning Guide.)