You can create messages and use them in your routine to indicate the status and progress of the routine during run time, and to display variable values. The process of creating messages and using them requires that you create a message source file, and convert the source file into loadable code for use in your routine.
You can use the Language Environment callable service CEEMOUT to direct user-created message output to the Language Environment message file. To direct the message output to another destination, use the Language Environment MSGFILE runtime option to specify the ddname of the file.
When multiple Language Environment® environments are running in the same address space and the same MSGFILE ddname is specified, writing contention can occur. To avoid contention, use the MSGFILE suboption ENQ. ENQ tells Language Environment to perform serialization around writes to the MSGFILE ddname specified which eliminates writing contention. Writing contention can also be eliminated by specifying unique MSGFILE ddnames.
Each Language Environment-conforming language also provides ways to display both user-created and runtime messages. (For an explanation of Language Environment runtime messages, see Interpreting runtime messages.)
The following sections discuss how to create messages in each of the HLLs. For a more detailed explanation of how to create messages and use them in C, C++, COBOL, Fortran, or PL/I routines, see z/OS Language Environment Programming Guide.