When planning the size of your pools, remember that the number of characters in the pool prefix determines the maximum pool size. A pool prefix consists of one to five alphanumeric, national, or special characters followed by an *, for example, ABADA*. Table 1 shows the maximum number of volumes each range of pool prefixes can contain:

The maximum numbers in Table 1 are for numeric suffixes. If you use nonnumeric suffixes, such as pool prefix A with suffixes A00000 through AZZZZZ, you can increase the maximum number of volumes for that pool. For example, using the suffix AAAAA* with alphanumeric characters, $, #, @, and the special characters, you can have a maximum of 51 volumes. However, by using nonnumeric suffixes, you limit the use of the COUNT operand on RMM TSO rack and volume related subcommands.

Plan ahead when choosing your pool prefixes, ensuring that the pool prefixes can satisfy all future volume quantities. It is not necessary to define all shelf locations to DFSMSrmm at once. Using pool definitions, you can reserve space for library expansion without taking up space in the control data set. For instance, you could assign a pool prefix ABC*, allowing space for 1000 volumes, but only defining shelves ABC000 - ABC099 initially.

When you use the VLPOOL NAME or SMS storage group name for scratch pooling, you can include multiple VLPOOL PREFIX ranges into the same scratch pool by specifying the same NAME value on multiple VLPOOL definitions or by assigning storage group names for each volume.