Unless you work for IBM, you do NOT need to know very much about the details of the CICS start up / shut down process. And if you do work for IBM, you will find out more internally than by posting on a forum. IBM does NOT publicize some of the details, so there are some details you cannot find out without working for IBM.
Have you looked at Redbook SG24-7952, CICS Transaction Server from Start to Finish ? This will tell you about all you need to know.