Unable to really find this information online anywhere, maybe someone here could point me to the right manual. Essentially I am curious if the Transaction Definitions are keep in memory of some kind? Some sort of address space, or is an I/O performed on the database anytime CICS needs this information. Thank you.
Tried researching online and did not find much information surrounding this specifically.
The CICS transactions definitions are defined into the CSD Dataset using either DFHCSDUP (batch program) or the online transaction CEDA. There are SPIs as well that will allow you to do these definitions as well (EXEC CICS CSD).
Using CEDA these definitions can then be installed into CICS for the region to use. You can also use EXEC CICS CREATE to install definitions into a CICS region without them being defined on the CSD.