Total cache size
In releases prior to z/OS V2R2, the total storage size available for all the caches in the zFS address space had to be less than 2 GB. If the cache sizes specified in the IOEFSPRM file were too large, zFS would terminate. In addition to the zFS address space caches, storage is necessary for processing file requests and for the products zFS might use. As a result, the total address space cache storage was restricted to approximately 1.5 GB. Use modify zfs,query,storage to determine the total allocated zFS storage. See STOR for more information about determining how much of the available zFS address space storage is being used by the zFS caches.
In z/OS V2R2, zFS uses 64-bit storage above the 2 GB line. Therefore, zFS cache sizes are no longer restricted by the 2 GB storage size. Caches start at the minimum size during zFS initialization, and are allowed to grow as needed to the size specified in the IOEFSPRM file. Carefully consider how large you want your zFS caches to be, taking into account such things as the amount of real and auxiliary storage in your system.
You might see messages IOEZ00188A, IOEZ00662I, or IOEZ00663I, which indicate that the zFS address space is low on storage. If it continues to be a problem, consider using zfsadm config to dynamically decrease the size of caches that do not reside in data spaces, such as the metadata or vnode caches.