Could you please let me know a layman explanation to what "books" means in mainframe terminology?
I am new to systems stuff & reading things, so pardon me if the term is common knowledge.
Googling lands me nowhere since the search term is "books".
I came across the terminolgy in the below context, (http://www.timothytuohy.com/pu_configs.htm)
Concurrent CP, IFL, ICF, zAAP, or zIIP upgrades are done within a z9 EC model. Concurrent upgrades require PU spares. PU spares are PUs that are not the two standard spares but those PUs that are not characterized as a CPs, IFLs, ICFs, zAAPs, zIIPs, or SAPs.
If the upgrade request cannot be accomplished within the given configuration, an upgrade is required. An upgrade will cause the addition of one or more books to accommodate the desired capacity. Additional books can be installed concurrently.
Upgrades from one z9 EC configuration to another are concurrent and mean that one or more books are added. However, there is an exception. Upgrades from any z9 EC model up to a Model S38 to a z9 EC Model S54 is disruptive since this upgrade requires a full book replacement.