re: Not sure on that one
IBM's Mainframe database *usually* does not contains fixes or if they do they are one or two line source fixes or byte updates to IBM modules.
SInce just about the only source IBM offers is to the JES system fixes tend to be small. There are exception to fixes for JES but then those longer ones are not posted publicly (although you might get level 2 to fax them to you).
Almost all IBM fixes replace then entire module and the applicability of the fix is determined by SMPE (maintenance program). At one time IBM shipped thousands of fixes every month and the maintenance program would figure out which fix applies to you level of the nodule being fixed, it really does not do any good to "copy" modules as the maintenance program will figure out if its applicable to your system.
IBM no longer does this (for reasons other that fear of stealing).
Some portions of JES are OCO and then IBM sends out complete module replacement for that portion.
OCO is Object code only NO SOURCE.
Having a module does not help you what so ever as it must match the other modules at the same level. This is extremely tricky to do but IBM does do it and without SMPE the million(this is a WAG) plus modules in an IBM system would be impossible to maintain.