SQL/MP Programming Manual for COBOL

Memory Considerations
HP NonStop SQL/MP Programming Manual for COBOL—529758-003
B-6
Guidelines for Memory Use
Do not count these SQL statements and directives:

BEGIN DECLARE SECTION and END DECLARE SECTION

CONTROL EXECUTOR, CONTROL QUERY, and CONTROL TABLE

DECLARE CURSOR

INVOKE

WHENEVER
Guidelines for Memory Use
The system allocates real memory in 16 KB pages. If an SQL statement uses only part
of a page, the system allocates the entire page. Therefore, the real memory used by
embedded SQL statements can be larger than the figures shown under Memory
Requirements on page B-5.
A program can encounter memory problems in these situations:

The program contains a large number of embedded SQL statements.

The program runs on a system with limited memory (for example, 16 MB or less).

The program runs in a CPU that is also running a large number of other programs.
To reduce the memory use in an extended data segment, follow these guidelines:

Declare only the host variables that your program actually requires.

Declare all host variables in one Declare Section. The system then allocates the
host variables contiguously in one or more pages, rather than allocating each host
variable in a separate page.

Execute SQL statements in listing order as often as possible. Therefore, the SQL
statements can share many of the pages in the extended data segment.

As a last measure, use dynamic SQL statements. Using dynamic SQL statements
can reduce memory use. However, it can also degrade a program’s performance
because of the additional SQL run-time compilations.
ALTER
BEGIN WORK
CLOSE
COMMENT
CREATE
DELETE
DESCRIBE
DESCRIBE INPUT
DROP
END WORK
EXECUTE
EXECUTE IMMEDIATE
FETCH
FREE RESOURCES
GET VERSION
HELP TEXT
INSERT
LOCK TABLE
OPEN
RELEASE
ROLLBACK WORK
SELECT
UNLOCK TABLE
UPDATE
UPDATE STATISTICS