HP NonStop SQL/MP User Manual

Memory Considerations
HP NonStop SQL/MP Programming Manual for C—429847-008
B-5
Avoiding Memory Stack Overflows
If a stack overflow occurs, the executor traps (trap number 3), sends a message to
the EMS collector process ($0), and then abends. You can read the EMS event log
for this message. For a description of the SQL/MP messages sent to the $0
process, see the SQL/MP Messages Manual. If a call to the file system causes a
stack overflow, the SQL executor returns SQL error 8003 and file-system error 22.
You can prevent a stack overflow in a C program by following these guidelines:

Use the large-memory model. Specify the XMEM pragma (the default) to select the
large-memory model and the XVAR pragma (also the default) to direct the
C compiler to allocate static aggregates in extended memory.

Allocate SQL internal data structures (SQLIN, SQLIVARS, and SQLOVARS) in
extended memory (which is the default for the large-memory model). The
SQLMEM pragma (USER or EXT) controls the placement of the SQL structures;
SQLMEM EXT (extended memory) is the default.

Use the Binder SET EXTENDSTACK command to extend the user stack space.
For more information, see the Binder Manual.

When you start the program, increase the number of data pages for the program
using one of these options:

Interactively, specify the MEM option to increase the data pages in the TACL
RUN command. For more information, see the TACL Reference Manual.

Programmatically, set the memory-pages parameter of the NEWPROCESS or
PROCESS_CREATE_ system procedure. For more information, see the
Guardian Procedure Calls Reference Manual.

HP NonStop SQL/MP Specifications

General

Brand	HP
Model	NonStop SQL/MP
Category	Software
Language	English