Data Set Options under OpenVMS

DEQ= Data Set Option: OpenVMS

Specifies how many disk blocks to add when OpenVMS automatically extends a SAS data set during a write operation.

Default:	enough blocks for five data set pages
Valid in:	DATA step and PROC steps
Category:	Data Set Control
Engines:	V9, V8, V7, CONCUR
OpenVMS specifics:	All aspects are host-specific

Syntax
Details
Example
See Also

Syntax

DEQ=default-file-extension-quantity

default-file-extension-quantity: can range from 0 to 65,535 blocks. (A block is 512 bytes.) If you specify a value of 0, OpenVMS uses the process's default value. The default value is enough space for five pages.

Details

You should set the value to at least 10 percent of the normal data set size. A large value results in fewer file extensions during the life of the file; a small value results in many file extensions over the life of the file. Note that record access is slowed when a file has many noncontiguous file extensions.

Example

Suppose you specify the DEQ= data set option as follows:

libname test '[mydir]';
data test.a(alq=1000 deq=1000);
   . . . more data lines . . .
run;

Specifying DEQ=1000 indicates that if more space is needed for the file, that space is allocated in 1,000-block chunks. Note that OpenVMS always rounds the DEQ= value up to the next disk-cluster boundary.