Starting an alternate JES2 subsystem as a primary subsystem

You can run an alternate job entry subsystem (JES) as a primary JES in place of the primary JES. To be run as the primary, start the alternate by using the name of the primary, because only the subsystem known to MVS™ as the “primary JES” can interface with TSO/E. To start the alternate, the procedure used to start the primary must have STEPLIB and HASPPARM DD statements that can be overridden by the START command. If these DD statements cannot be overridden, the required JES cannot be loaded to replace the primary JES.

To execute a different copy of JES2 as a primary subsystem, one of the following procedures should be used. If the primary member specified at system installation is automatically started, it must be stopped before initialization. You can stop the primary member either by specifying a CONSOLE statement in the JES2 initialization data set or on the MVS START command. Then reply:

  Rnn,$PJES2

when the member prompts you with the $HASP426 message.

If the primary was not automatically started or was prevented from initializing by the previous procedure, then enter the command S JES2, overriding the data set name and the volume serial on the STEPLIB DD statement to point to the load library containing the alternate subsystem.

The following is a sample procedure that will run either the normal JES2 or any alternate version of JES2 as a primary job entry subsystem:

Figure 1. Sample procedure

  //JES2      PROC  M=JESAPARM,U=3380,L=LINKLIB,N=SYS1,
  //                V=SYSRES
  //IEFPROC   EXEC  PGM=HASJES20,TIME=1440
  //STEPLIB   DD    UNIT=3380,VOL=SER=&V,DISP=SHR,
  //                DSN=&N;.&L;
  //PROC00    DD    DSN=SYS1.PROCLIB,DISP=SHR
¹ //HASPPARM  DD   DSN=&SYS1;PARMLIB.(&M),DISP=SHR,UNIT=&U;
  //HASPLIST  DD    DDNAME=IEFRDER

Note: Libraries specified in the JES2 procedure must be referenced in one of the following ways:

Cataloged in the master catalog (or in a user catalog, provided the data set has a high-level qualifier other than SYS1)
Specify UNIT= and VOL= on the JCL DD statement
Managed by SMS (UNIT= and VOL= on the JCL DD statement are ignored.)

To cause JES2 to be loaded from an alternate library (TEST.LINKLIB on TSTPAK), and to cause an alternate member of SYS1.SHASPARM to be used for JES2 initialization, create a member in SYS1.SHASPARM. Then, enter the following command:

S  JES2,N=TEST,V=TSTPAK,M=TESTPARM

To make the secondary test JES2 the primary JES2 member when you have finished testing, issue the following MVS command:

S  JESA,JOBNAME=JES2

This command starts the 'JES2' job as a started task. For more information about this procedure, see Specifying a back-up JES2 cataloged procedure.

Note: JES2 starts each functional subsystem (FSS) through an internal STARTcommand. This command cannot contain variable operands to specify STEPLIB information. If multiple versions of JES2 are maintained in separate libraries, you might need to maintain multiple versions of the FSS cataloged procedure(s) and vary the PROC= keyword of the FSS initialization statements to ensure that the correct version of the HASPFSSM load module is used.