Has anyone noticed? What used to be a single IBM DB2 manual is now two separate manuals. IBM has split the Messages & Codes manual into one manual for Messages and a separate manual for Codes. The links in the previous sentence take you directly to the web versions of the manuals. If you prefer to download PDF documents, use this link for DB2 V8.
So, if you are looking for the meaning of a DSN message you would use the Messages manual; if you are looking for a SQLCODE or SQLSTATE, use the Codes manual. I kinda liked them both in one manual, but I guess the combined manual was getting a bit too big to manage...
Also, if you haven't used it already you might want to become familiar with LookAt. LookAt is an online facility for displaying explanations for most IBM messages, as well as for some system abends and codes.
You can use LookAt on the web at: www.ibm.com/eserver/zseries/zos/bkserv/lookat/
Or, you can use it from anywhere you can access a TSO/E command line. Of course, to use LookAt as a TSO/E command, LookAt must first be installed on your system. You can get the LookAt code via ftp at ftp.software.ibm.com/ps/products/ibmreader/tools/lookat/ZOS/