maxtsiz.5 (2010 09)

m
maxtsiz(5) maxtsiz(5)
(Tunable Kernel Parameters)
NAME
maxtsiz, maxtsiz_64bit - maximum size (in bytes) of the text segment for any user process
VALUES
Default
32 bit:
96MB
64 bit: 1GB
Allowed values
32 bit minimum: 0x40000
32 bit maximum: 0x40000000
64 bit minimum: 0x40000
64 bit maximum: 0x3FFFFFFFFFF
DESCRIPTION
User programs on HP-UX systems are composed of five discrete segments of virtual memory: text (or
code), data, stack, shared, and I/O. Each segment occupies an architecturally defined range of the virtual
address space which sets the upper limit to their size. However, text, data and stack segments may have
a smaller maximum enforced via the maxtsiz, maxdsiz and maxssiz tunables.
maxtsiz controls the size of the text segment, which is the read-only executable object code for the pro-
cess that can be shared by multiple processes executing the same program. For example, all copies of vi
on the system use the same text segment.
The limit enforced by
maxtsiz is not applicable for HP-UX 32-bit MPAS (Mostly Private Address Space)
executables. For 32-bit MPAS executables, the only limit is that the entire address space of the process
cannot exceed 4GB. See the Adaptive Address Space Whitepaper for details.
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect immediately. The size is expected to be a multiple of the base page
size. See the description of
_SC_PAGE_SIZE
in getconf (1) for more details. If the value specified is not a
multiple of the base page size, it will be rounded down to the nearest multiple of the base page size.
When Should the Value of This Tunable Be Raised?
maxtsiz should be raised if user processes are receiving the [ENOMEM] error with the following mes-
sage:
exec(2): text exceeds maxtsiz
or
exec(2): text exceeds maxtsiz_64bit
What Are the Side Effects of Raising the Value?
None.
When Should the Value of This Tunable Be Lowered?
This tunable should be lowered to limit the text size of running processes; there is no system performance
reason to do so though.
What Are the Side Effects of Lowering the Value?
None.
What Other Tunable Values Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its
meaning changed in future releases of HP-UX.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parame-
ter values. After installation, some tunable parameters may no longer be at the default or recommended
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1