TABLESIZE Option

Set and subset entries are normally grouped in tables. Users can control the size of these tables using the TABLESIZE (or BLOCKSIZE) option. TABLESIZE can be specified in one of the following options:

  • 0 Words – the maximum value is 4095.

  • 0 Segments – the maximum value is 136 segments. This is equivalent to 4095 words rounded down to segments.

  • 0 Bytes – The maximum value is 24570 bytes. This is equivalent to 4095 words.

  • 0 Entries – This is the default unit. The maximum value is 4095 entries.

Note: For recommendations about table size values in anticipation of the deployment of 512-byte physical sector technology, refer to “Preparing for Open Disk Technology” at the beginning of this section.

Each table occupies an integral number of segments on disk. If the number of entries for each table does not use an integral number of segments, then the remainder of the last segment of each table is not used.

When no TABLESIZE is specified, DASDL automatically computes a default value, taking in consideration the value of ADDRESSCHECK, CHECKSUM, and other control words. For index sequential sets and subsets, the system chooses a table size that is as small as possible yet minimizes the number of table levels. For index random sets and subsets that specify a modulus, the system selects a table size that is as small as possible while minimizing the number of overflow tables. DASDL tries to choose a default table size that is less than 1000 words.

Consider the explicit or implicit setting of control words when calculating set‑subset specifications for the TABLESIZE option.

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