The fallback procedure is fairly simple. The only libraries that are modified by the upgrade process are ADRLIB, ADRPNL and ADROUT. When you do the upgrade, a copy of your r14 libraries are retained and it is highly recommended you keep the copy of your r14 libraries, just in case you need to fallback. So the procedure to fallback to CA Ideal r14 would be to change the JCL members and CICS configuration to point back to the r14 libraries. Remember, you will lose access to any output in ADROUT and any printer definitions that had been added in CA Ideal r15. Since the jobcards are stored in ADRLIB, you will also lose access to any new jobcard that was created.
IDDAT, IDDVW and SRC/PNL/OBJ libraries are not modified by the upgrade process.
Note: Because of the new Document Feature in CA Ideal r15, CA Ideal r15 needs to run with CA IPC r15 and CA Datacom/DB r15. If you have created any documents in CA Ideal r15, and you fallback to CA Ideal r14, you will not be able to use the documents you have created.