The role of volumes in automatic assignment

To begin the automatic assignment of data sets to volumes, you can make some of your existing volumes available to the dialog for creating the new system, or you can have the dialog create a configuration based entirely on new volumes. During automatic assignment, the dialog assigns data sets to these volumes. If the dialog requires additional volumes to contain the new configuration, the dialog creates more volumes automatically.

If you are installing a z/OS® order, you will restore the root file system into a single data set. For the root file system to be allocated as a single data set, you can place your z/OS root file system on a large DASD volume (generally larger than 3390-3), or use multiple volumes for the z/OS root file system data set (if you only have 3390-3 volumes available). Subsystem orders typically do not contain large file system data sets, so the amount of space to use might be smaller than z/OS. Note that the default volume value is 3390-9 in the dialog. If you are using smaller values for new volumes, you need to change the default volume to match.