ARM couple data set versioning

Automatic restart management allows different levels or functional versions of ARM couple data sets to be defined. The following couple data set format levels or functional versions can be created using the IXCL1DSU utility.

Base format level. This is the initial or base ARM couple data set format level and is created when the ARM couple data set is formatted using a version of IXCL1DSU prior to z/OS® V1R4.
z/OS V1R4 format level (HBB7707 SYMBOL TABLE SUPPORT). This format level is created when the ARM couple data set is formatted using a version of IXCL1DSU at z/OS V1R4 or higher.

ARM couple data sets formatted with the z/OS V1R4 version of IXCL1DSU are required in order to support the larger symbolic substitution table that is available in V1R4. Systems at different system levels can access the V1R4-formatted ARM couple data set.

Using the z/OS V1R4 version of IXCL1DSU, define new primary and alternate ARM couple data sets.
Enable the new Version 2 couple data set as the primary couple data set as follows:
If there is already a primary ARM couple data set enabled in the sysplex (by another active system in the sysplex), use the SETXCF COUPLE system command to enable the Version 2 couple data set as the alternate couple data set and then use the SETXCF PSWITCH system command to switch the alternate couple data set to the primary couple data set.
```
SETXCF COUPLE,TYPE=ARM,PSWITCH
```

These commands should be issued from a system where the ARM couple data set is enabled as the primary.

Once the Version 2 ARM couple data set is enabled as the primary couple data set in the sysplex, V1R4 systems can be IPLed into the sysplex.