COBOL Manual for TNS and TNS/R Programs

Procedure Division
HP COBOL Manual for TNS and TNS/R Programs—522555-006
8-42
Arithmetic Operations
The value of the file position indicator becomes undefined when an operation exceeds
its time limit. Because you cannot determine where in the operation the time limit was
exceeded, you cannot necessarily try the operation again immediately at the current
record.
Overhead
When a file is opened with timed I-O enabled, each I-O statement incurs more
overhead than a file opened without a time limit. Avoid using timed I-O unnecessarily.
When a file is being read with APPROXIMATE positioning, the value used for time limit
must take into account that a READ can take somewhat longer than expected. This
can occur when a nonexistent record is sought, because the operating system
searches through the file looking for the next defined record before reporting the
absence of the record sought.
Fatal Error
If a file is opened without the TIME LIMIT phrase, and the TIME LIMIT phrase is
specified in a LOCKFILE, READ, or START statement with a nonnegative value for the
time limit, a run-time error is reported to the process’s home terminal, and the process
terminates abnormally with the I-O status code “90”.
$RECEIVE Timeout
A process that must avoid unnecessary suspension when checking for messages on
$RECEIVE can use timed I-O. If the READ statement specifies the time limit 0 and no
message is present, the request times out immediately.
Arithmetic Operations
Many different statements tell the compiler to perform arithmetic operations, either
because they are arithmetic statements or because they include arithmetic
expressions.
The arithmetic statements are:
•
ADD
•
COMPUTE
•
DIVIDE
•
MULTIPLY
•
SUBTRACT