but still I couldn't find the list of all parameters used at IPL. Appreciate any advice.
I think one of the real problems is that you have not clearly defined what you are looking for. Certain values, such as the system programmer-supplied values mentioned in http://publib.boulder.ibm.com/infocente ... temIPL.htm
are external to the system and are not reflected in any data set on the system, although they are available for retrieval once the system IPL is complete. SYSn.IPLPARM (where n can vary from 0 to 9) is customized for each system and contains initial IPL parameters such as the master catalog name. SYS1.PARMLIB (which is a shortcut term for the dataset used by the system to load parameters -- the actual name will depend upon the site) is where many of the various system parameters are stored; there are well over 100 members in this data set and some of these members have dozens (or hundreds) of lines of parameter values.
Different control blocks have different parameters, but as has been pointed out already there are perfectly good programs available (MXI, SHOWZOS, IPLINFO are three of them) and material from the CBT has no cost -- so what you want to develop is already available at no cost to your site. Other than doing this as a learning exercise, there is no reason for you to proceed any further with your program. And if you do not have a deep understanding of the z/OS IPL process and the various control blocks of z/OS, you're going to have a very hard time doing what you want, anyway.
Asking for help with something like this on a beginner's forum isn't the best use of everyone's time, either.