COBOL Manual for TNS and TNS/R Programs

Environment Division
HP COBOL Manual for TNS and TNS/R Programs—522555-006
6-42
FILE-CONTROL Paragraph
RESERVE clause
enables or prevents sequential block buffering on input and buffered cache on
output, or enables or prevents HP COBOL Fast I-O for both input and output, for a
disk file, depending on the value of number. The access mode of the file must be
SEQUENTIAL.
number
is a numeric literal, an unsigned integer.
In the non-CRE environment, number must be in the range 1 through 8, and
its value is interpreted:
In the CRE, number must be in the range 1 through 32, and its value is
interpreted:
Value of number Effect
1 No buffering or HP COBOL Fast I-O
2 or greater Sequential block buffering for input and buffered cache for
output if the assigned file qualifies
number is the number of blocks to buffer.
Value of number Effect
1 No buffering or HP COBOL Fast I-O.
2 Sequential block buffering on input and buffered cache on
output if the assigned file qualifies.
3 or greater HP COBOL Fast I-O if the assigned file qualifies; if not,
sequential block buffering for input and buffered cache for
output if the assigned file qualifies; otherwise normal I-O
number is the number of blocks to buffer.
Caution. Do not use sequential block buffering for a file opened for shared access. If you do,
a process could read outdated data while another process alters the file. For information on
shared access, see OPEN
.
RESERVE
AREAS
AREA
number
VST040.vsd