If you are using a version of DB2 before DB2 LUW V5, the maximum length of the host variable is 30 characters. The preprocessor automatically adds 3 characters to a host variable name to make it unique unless you specify directive DB2(NOQUALFIX) to turn this feature off.
Resolution:
Specify the DB2(NOQUALFIX) compiler directive, and recompile the program. If you still get the error, make sure the host variable is a valid COBOL name of 30 characters or less in length.