pa_maxssiz(5)							File Formats Manual						     pa_maxssiz(5)

NAME

       pa_maxssiz: pa_maxssiz_32bit, pa_maxssiz_64bit - maximum size (in bytes) of the stack for a user process running under the PA-RISC emulator
       on an Integrity system

VALUES

   Default
   Allowed values
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.

       PA-RISC binaries running under Itanium-based system using the PA-RISC emulator have their stack segment size (which includes both the  mem-
       ory stack and the RSE stack) determined by or

       The emulated stack from the process perspective is the same as the stack if the process were executed on a PA-RISC machine without the emu-
       lator.  The actual (non-emulated) process stack (both memory and RSE) for an emulated process are of a non-configurable size and  are  used
       solely  for the internal use of the emulator for a PA-RISC process on Itanium-based system.  This tunable therefore represents the required
       value of or on a corresponding PA-RISC machine to execute the emulated process plus working space for the emulator itself.

       As with the stack address space sized by the address space used by the emulator is both private to the process and  not	usable	for  other
       purposes  regardless  of  whether  the emulator stack grows to encompass the full range or not.	As a consequence, the tunable value may be
       viewed as an amount of process data address space which will be unavailable to this PA-RISC process.  Caution is advised especially for	32
       bit processes since the default address space model only provides 1 Gb of private data space.  Setting this tunable too high will result in
       execution failure when other allocations (private calls or calls) fail due to insufficient available address space.  If this occurs, revise
       the address space model of the failing PA-RISC executable using to allow more private data virtual address space or lower the tunable.

   Who is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Given  that  the  user  memory stack size is not modifiable by this tunable, it is expected that detailed knowledge of the PA-RISC emulator
       memory usage is needed before modifying this tunable.

   When Should the Value of This Tunable Be Raised?
       This tunable should be raised if the PA-RISC emulator on Itanium-based system requires additional space for stack emulation.

   What Are the Side Effects of Raising the Value?
       The PA-RISC emulator will use more of the virtual address space for stack, leaving less virtual address space for data allocations.   Rais-
       ing the value too high will result in application failure when data allocations fail due to insufficient virtual address space.

       Since it may not be known which processes are based off of PA-RISC binaries and which off Itanium-based binaries, arbitrary raising of this
       tunable is discouraged.

   When Should the Value of This Tunable Be Lowered?
       This tunable should only be lowered if the workload for the PA-RISC emulator is known on the system, more space than is needed is currently
       used for stack emulation, and swap space (either reserved or allocated) is at a premium on the system.

   What Are the Side Effects of Lowering the Value?
       Lowering  this  tunable	will decrease the available stack space for emulated PA-RISC binary executions.  Emulated processes needing larger
       stacks will fail stack growth requests (just as lowering or may cause process termination due to failure to grow stack).

   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 parameter values.  After installation,
       some tunable parameters may no longer be at the default or recommended values.  For information about the effects of installation  on  tun-
       able  values,  consult  the documentation for the kernel software being installed.  For information about optional kernel software that was
       factory installed on your system, see at

AUTHOR

       was developed by HP.

SEE ALSO

       chatr(1), mmap(2), sbrk(2), maxssiz(5).

Integrity Systems Only					     Tunable Kernel Parameters						     pa_maxssiz(5)