The CICS Transaction Server for z/OS messages and codes is for anyone who needs to understand and respond to CICS.
1.) DFH messages - DFH01 to DFHM
CICS produces different types of messages for different users of the product. The messages are intended as a quick reference to get started with problem determination.
2.) Transaktion Abend codes
When abnormal conditions occur, CICS can send a message to the CSMT transient data destination containing the transaction ID, the program name and the abend code.