Db2 hash spaces 
(deprecated)
A hash space is a defined disk space that organizes table data for hash
access. Hash-organized
table spaces are deprecated and likely to be unsupported in the future.
FL 504 Hash-organized tables are deprecated. Beginning in Db2 12, packages that are bound with APPLCOMPAT(V12R1M504) or higher cannot create hash-organized tables or alter existing tables to use hash-organization. Existing hash-organized tables remain supported, but they are likely to be unsupported in the future.
When you organize a table for hash access, Db2 requires a defined amount of disk space to contain table data. You can specify the amount of disk space to allocate to the hash space when you create a table or alter an existing table. The hash space on a table must be large enough to contain new rows that are added to the table. If a hash space is full, new rows are relocated to the overflow index, which reduces the performance of hash access on that table. Hash spaces can contain only a single table in a partition-by-range or partition-by-growth table space.