An APPL definition statement defines an application program to VTAM®. Because TCAS and each TSO user are VTAM application programs, you must code APPL definition statements for them and put the definition statements in SYS1.VTAMLST.

You can reduce the number of operands you need to code on the APPL definition statements for each TSO user by using the GROUP definition statement under the APPL major node. All of the operands on the APPL definition statement except ACBNAME can be coded on the GROUP definition statement and allowed to sift down. You only need to code the unique name on the APPL definition statements for the TSO users if you use the GROUP definition statement to specify all the other operands.