The CLIST executes each statement or command after performing symbolic substitution on it. Therefore, when you use the MSG option with LIST and CONLIST, messages about execution errors appear at the terminal after the line that caused the error.

For example, the CLIST in Figure 1 fails when the input data set is not cataloged. When the input data set is not cataloged, the CLIST displays the following information at the terminal, with messages after the statement that failed to execute.

SET INPUT = data.set.name
SET INPUT = data.set.name
SET DSN = &INPUT;
SET DSN = data.set.name
allocate file(a) dataset('myid.&dsn')
allocate file(a) dataset('myid.data.set.name')
IKJ56228I DATA SET MYID.DATA.SET.NAME NOT FOUND IN CATALOG
OR CATALOG CANNOT BE ACCESSED
IKJ56701I MISSING DATA SET NAME+ 
IKJ56701I MISSING NAME OF DATA SET TO BE ALLOCATED
 

The diagnostic output ends after the ALLOCATE command, when the CLIST detects the error. Working backwards from the last line, you can find and correct the source of the error (in this case, the value of &INPUT).

Note that the last line in Figure 1 is a continuation of the preceding message line. When the CLIST is executed under ISPF, the continuation is displayed as shown in Figure 1. Under line-mode TSO/E, you must type a question mark (?) after the plus sign to see the continuation.