Size of the VTAM request unit (RU)

A VTAM® request unit (RU) contains system data information for a printer. An increase in VTAM RU size might increase printing rate, because processing larger (and therefore fewer) RUs contributes to higher efficiency.

The maximum size of the RU, however, is limited and dependent upon the limitations of hardware and software. For example, the RU size is limited by the communications controller or by the maximum buffer size allowed by the printer, whichever is smaller. Generally, use the largest RU size suitable for the printer or attachment being used.