MFMDS040E VSAM error DD=ddname RC=nn FB=nnn REQ=verb

DSS has detected a VSAM error probably associated with an input/output operation on an item library. Possible values for verb include:
Verb Description
GET Read a record
PUT Write a record
CHECK Verify completion of an event
POINT Position to a specific location
ENDREQ Cancel an operation
ERASE Erase a record

Common return code (RC) values and feedback code (FB) values include:

RC FB Description
8 8 Attempt to store a duplicate key
12 Conflicting options specified violate stored sequence
16 Record not found
20 Physical locking conflict
24 Volume not available
28 Insufficient space on volume to extend the
32 Invalid relative byte address specified
36 Key range specified in definition excludes this key
40 Insufficient virtual storage in the Mainframe Access address space
48 Conflicting options on VSAM request
64 No virtual storage to handle this level of concurrency
68 File not open for type of processing requested
72 Keyed request made to an ESDS
88 Invalid switch to sequential processing without positioning
92 Invalid replace or erase without key
96 Attempt to modify a key on update
104 Conflicting RPL options
108 Invalid record length specified
112 Invalid key length specified
4 Read error on data component of file
8 Read error on index component of file
16 Write error on data component of file
20 Write error on index component of file

For a full list of return codes and reason codes see the IBM publication DFSMS/MVS Macro Instructions for Data Sets.