You can store logon procedures in either SYS1.PROCLIB or in an installation data set. SYS1.PROCLIB cannot be shared among systems in a multiple system complex. If you want to share logon procedures among systems, you must place them in an installation data set that can be shared.

If you use an installation data set, the data set must be partitioned, and contain logon procedures only. Note that the name of a TSO/E logon procedure must not be the same as any subsystem.

If you use JES2, code a PROCxx DD statement to define the data set in the procedure for starting JES2. Use the TSUCLASS initialization statement to refer to the DD statement. For more information about specifying the TSUCLASS initialization statement, see .

If you use JES3, code an IATPLBxx DD statement to define the data set in the procedure for starting JES3. Use the STANDARDS initialization statement to refer to the DD statement. For more information about specifying the STANDARDS initialization statement, see .

Like other tasks, some of the JCL for a time shared task for a TSO/E logon is created automatically. The system generates a JOB and EXEC statement and gives control to the TSO exits that allow the installation to manipulate the values that are placed on the JOB and EXEC statements. In addition, TSO/E copies the characteristics specified in the logon panel to the JOB statement. The procedure name specified on a logon panel is placed in the EXEC PROC field to indicate which procedure to use. TSO/E procedures must be single-step procedures.

TSO/E logon procedures are started under the primary job entry subsystem (JES). A JES initialization statement determines the library that contains the TSO/E logon procedure. (Often, TSO/E logon procedures are separated from other procedures.)

In a JES3 environment, the JCL used to submit a TSO/E logon is limited to approximately 700 cards. For JES2, the limit is slightly more that 400.