SET TBUFSIZE

Purpose

Specify size of terminal output buffer to optimize terminal I/O throughput.

Syntax

SET TBUFSIZE TO <expN>

See Also

SET DCACHE, SET ICACHE, SET PCACHE, SET SCREENMAP

Description

The SET TBUFSIZE TO <expN> command allows for the specification of the size of the terminal output buffer. All output to the terminal is stored in this output buffer until either the buffer is full, or a terminal read is requested. Certain commands can take a long time to automatically flush the terminal output buffer.

A large value for this setting enables forms to be displayed using one Operating System write request, thereby minimizing Operating System overhead, and taking advantage of any DMA communications controllers. The form is also displayed on the screen more smoothly.

On OpenVMS, the maximum setting of TBUFSIZE depends on the value of the SYSGEN parameter MAXBUF and the maximum buffered I/O quota in the user authorization entry for the user. Terminal Developer inspects the size of the MAXBUF parameter and sets TBUFSIZE as high as possible. The OpenVMS Systems Manager can make adjustments so that Terminal Developer users can take advantage of an increased TBUFSIZE. To take full advantage of a large TBUFSIZE on OpenVMS, the terminal should be set to DMA, using the DCL command:

$ SET TERMINAL/DMA

Example

set tbufsize to 3000

Products

Recital