In z/OS® V1R8, the master console has been removed. The value of the master console has decreased over time. Historically, the master console had been used for important messages that required the highest level of authority to take action.
Table 1 details the functions that were unique to the master console that are now available to other consoles.
| Functions | z/OS V1R7 and lower releases | z/OS V1R8 and higher releases |
|---|---|---|
| Routing codes 1 and 2 | The master console was forced to have routing codes 1 and 2 assigned to it and they could not be removed. | Routing codes 1 and 2 are no longer forced to any console. Make sure routing codes 1 and 2 are assigned to the appropriate console definitions in CONSOLxx. |
| Console id 0 ( internal console ID (X’00000000’)) | All messages targeted for console id 0 were delivered to the master console. | All messages targeted for console id 0 will go to any console that has the INTIDS routing attribute. INTIDS may be specified in CONSOLxx or through the VARY CN command. |
Table 2 details the functions that affected the master console that have been changed.
| Functions | z/OS V1R7 and lower releases | z/OS V1R8 and higher releases |
|---|---|---|
| External interrupt key | The external interrupt key was used to switch the master console function to another console. | Since there is no longer a master console the external interrupt key on the hardware management console is not supported. |
| SYNCHDEST | The master console (*MSTCON*) could be specified in the SYNCHDEST group as a destination for synchronous messages. | The master console (*MSTCON*) is ignored. You need to explicitly specify by name any consoles you expect to receive synchronous messages. The system console remains the synchronous message destination of last resort. |
| Synchronous message destination default (no SYNCHDEST group defined) | The master console was used if available on the system where the message was issued, otherwise the system console on that system was used. | The system console on the system where the message was issued is used. |
Table 3 details the remaining functions that were affiliated with the master console and removed.
| Functions | z/OS V1R7 and lower releases | z/OS V1R8 and higher releases |
|---|---|---|
| Console switch and the SWITCH CN command | Console switch and/or the SWITCH CN command was used to switch a failing console to an alternate console. | The main purpose was to ensure the availability of the master console. Since the master console has been removed the need for console switch and SWITCH CN command has also been removed. This reduces the complexity of console definitions and the difficulties of finding the location of the master console after a console switch. |
| Hardcopy switch | Depending on your configuration of OPERLOG and SYSLOG, when one failed, hardcopy could automatically switch to the other. | There is no switching between hardcopy mediums, therefore to maintain the same level of functionality, run with both SYSLOG and OPERLOG as your hardcopy medium. |
| ALTGRP (alternate group) | The ALTGRP function was used in selecting an alternate console. | There is no longer a need for the ALTGRP (alternate
group) function because of the elimination of console switch. Note: The
Parmlib(CNGRPxx) member is still used for AUTOACT and SYNCHDEST. In
V1R8 and higher the ALTGRP(x) keywords need to be removed from the
CONSOLxx parmlib member.
|
| NOCC and NOMCC | NOCC (no consoles condition) and NOMCC (no master console condition) were considered to be undesirable conditions. NOCCGRP specification in CONSOLxx specifies the name of the console group defined in CNGRPxx from whose members the system or sysplex can select a master console during a no consoles condition. | NOCC and NOMCC are no longer considered undesirable conditions and can be considered an acceptable running console environment. The specification of NOCCGRP is ignored. |
Table 4 details the functions changed to help run your sysplex.
| Functions | z/OS V1R7 and lower releases | z/OS V1R8 and higher releases |
|---|---|---|
| SYSCONS (system console or hardware management console) | SYSCONS authority was installation defined. | SYSCONS always has master authority to insure there is always a master authority console available. |
In V1R7 the external use of 1 byte console IDs was removed. If you compiled a program that used 1 byte console IDs, compilation would fail. But existing compiled programs that used 1 byte console IDs would continue to execute as before.
In z/OS V1R8 and higher releases, 1-byte console IDs (and EMCS migration ids) are eliminated. All messages targeted for 1 byte console IDs will go to any console that has the UNKNIDS routing attribute. UNKNIDS may be specified in CONSOLxx or through the VARY CN command.