The CICS® parameter manager domain loads a system initialization table (SIT) at the start of the initialization process. You specify the SIT that defines the CICS characteristics appropriate to your needs by coding the suffix of the DFHSITxx load module (where xx is the suffix) on the SIT= system initialization parameter. If you fail to specify the suffix of a SIT, then CICS tries to load an unsuffixed module.
You can modify many of the system initialization parameters dynamically at the beginning of CICS initialization by providing system initialization parameters in the startup job stream, or through the system console. There are also some system initialization parameters that you cannot code in the SIT, and can only supply at startup time. You specify system initialization parameters at startup time in any of three ways:
You can use just one of these methods, or two, or all three. However, CICS processes these three sources of input in strict sequence, as follows: