How You Alter System Definitions While CA MIM Executes

The ALTERSYS command lets you:

Modify an existing system definition with a status of FREED or DISABLED
Avoid using the SYSID execution parameter override and maintain correct system definitions (DISPLAY SYSTEMS)

Issue the ALTERSYS command dynamically after CA MIM is synchronized.

This example shows you how to modify a system definition. Here we are changing SYS32 with alias 32 to SYS33 with alias 33.

Follow these steps:

Shutdown and FREE SYS32.
Issue the ALTERSYS command in the following format:
```
ALTERSYS SYS32,NAME=(SYS33,33),STATUS=ENABLED
```
The ALTERSYS command changes the CA MIM system name from SYS32 to SYS33 and the CA MIM system alias to 33.
Verify the modification was successful by issuing the DISPLAY SYSTEMS command.
Replace the DEFSYS entry for SYS32 with an entry for SYS33 in your shared CA MIM initialization parameter member.
Start SYS33.

After a system definition is altered:

The system is marked DISABLED (unless the STATUS keyword specifies ENABLED) and cannot join a currently executing MIMplex.
Systems are marked DISABLED after a name alteration to prevent the use of that definition until it is explicitly enabled.
You can explicitly enable the disabled system using the ALTERSYS STATUS=ENABLE command.
If a DISABLED system attempts to join a currently executing MIMplex, the system is forced to terminate with a U0040 ABEND.