Description of control parameters

In many cases, the default values of the control parameters are sufficient. However, it may occasionally be useful for the BS2000 system administrator to adapt the control parameter to suit the specific POSIX application and the resources of the overall system. The control parameters for which modification can be useful are listed below. The meaning of every control parameter is also specified.

General system parameters
FILESIZE	Maximum size of a file for creating and writing. The maximum value preset is 1024 Gbyte. For reasons of compatibility, UNLIMITED64 can also be specified instead of UNLIMITED.
FLCKREC	Number of locking structures used by the system for data records (record locks).
HDPTNI	Maximum number of mounted local file systems.
HDSTNI	Number of server tasks for performing asynchronous I/Os.
HEAPSZ	Maximum value possible for brk() system call.
KMAHWM	If the dynamic Cl-4 memory map in POSIX exceeds the specified value, the kernel memory daemon will be activated to reorganize and release the memory.
MAXUP	Maximum number of processes which a nonprivileged user can start simultaneously (not for each terminal but all together).
MINPAGEFREE	No meaning, as it cannot be set. MINPAGEFREE is implicitly set to 128 K, i.e. if less than 128 K is free in the buffer cache, pageout will be activated.
NOFILES	Maximum number of open files in the system.
NPBUF	Maximum number of I/O buffers for physical I/Os. This value should be at least 4 * HDSTNI.
NPROC	Maximum number of user processes allowed in the system.
PGOVERFLOW	Number of reserved I/O buffers for pageout even with a memory bottleneck.
File system parameters
BUFHWM	Size of memory (in kilobytes) which can be occupied by the I/O buffer.
FDFLUSHR	Time interval (in seconds) between two activations of a process. fsflush writes data from the cache to the hard disk, and thereby ensures the consistency of the data on the hard disk. A low value for FDFLUSHR offers greater security against data loss in the event of a system crash, albeit at the expense of system performance.
NAUTOUP	Specification (in seconds) of how long a buffer must “age” in memory before it is reloaded by fsflush. This value only affects the contents of the cache buffer.
NBUF	Number of I/O buffers of the cache buffer which are assigned by the system kernel if no more are free.
NHBUF	Number of hash anchors for rapid access to cache buffers via device and block numbers.
NRNODE	Maximum number of NFS-rnode structures. These are specific descriptors for open files from NFS file systems, i.e. these files are located on remote computers.
SEGMAPSZ	Maximum size of the cache buffer in class-4 memory (in units of 8KB). This parameter only has an effect on the I/O throughput under certain conditions. Generally, i.e. on hardware with data space support, the cache buffer of the POSIX kernel is kept in data spaces and not in class-4 memory, and this parameter has no effect.
UFSNINODE	Maximum number of UFS index entries in the system kernel.
Control parameters for interprocess communication
Message queues and semaphores are administered via resource maps. Resource maps keep a record of how much memory space is used by messages and semaphores. The number of occupied entries of a resource map at a given time serves as a measure for the current partitioning of the memory area available for messages or the available semaphores. If control parameters such as MSGSEG or SEMMNS are increased, the size of the corresponding resource map should also be increased accordingly.
MSGMAP	Number of entries in the resource map for message queues.
MSGMAX	Maximum size of a message (in bytes).
MSGMNB	Maximum total size of all messages in a message queue (in bytes).
MSGMNI	Maximum number of message queues throughout the system.
MSGSEG	Number of message segments in the system. If the value of MSGSSZ is multiplied by the value of MSGSEG, the result is the total memory space which is available for message data.
MSGSSZ	Minimum allocation size for message memory (segment size in bytes).
MSGTQL	Number of message headers in the system. This number corresponds to the number of outstanding messages.
SEMAEM	Maximum undo value for one semaphore.
SEMMAP	Number of entries in the resource map for semaphore records.
SEMMNI	Maximum number of semaphore records.
SEMMSL	Maximum number of semaphores per record.
SEMMNS	Maximum number of semaphores in the system.
SEMMNU	Maximum number of processes with outstanding undo operations. Processes can determine whether their semaphore actions are to be automatically undone at the end of the process.
SEMOPM	Maximum number of semaphore operations that can be executed per semop(2) system call.
SEMUME	Maximum number of undo operations per process.
SEMVMX	Maximum value for one semaphore.
SHMMAX	Maximum size of a shareable memory area (in bytes).
SHMMIN	Minimum size of a shareable memory area (in bytes).
SHMMNI	Maximum number of shareable memory areas.
SHMSEG	Maximum number of shareable memory areas which a process uses simultaneously.
Special parameters for POSIX
BINDANY	The BINDANY parameter is meaningless as of BCAM Version 13.
DBLPOOL	To speed up the loading process for Posix shell commands and other POSIX programs with the POSIX loader, a value greater than zero may be entered here (in MB). See also section “POSIX loader”.
DBLSTATE	Specifies whether the POSIX loader is automatically activated when the POSIX subsystem is started up: 0=no (default); 1=yes.
FORCEDTERM	Forced termination of the POSIX subsystem. If connections exist, this parameter controls whether a second STOP-SUBSYSTEM command with the parameter SUB-PARAMETER='FORCED-BY-SUBSYSTEM' must be issued, or whether the subsystem is to be stopped immediately without a second STOP-SUBSYSTEM command. FORCEDTERM=0 (previous behavior) FORCEDTERM=1 (forced termination)
MAXTIMERC	Maximum wait time for completing the rc termination procedures when terminating POSIX.
NOPTY	Maximum number of physical terminals (device dev/pts). This corresponds to the permissible number of rlogin and telnet accesses.
NOSTTY	Maximum number of system file terminals (device dev/sf) supported by POSIX. This corresponds to the permissible number of POSIX accesses via BS2000 procedures and programs.
NOTTY	Maximum number of block terminals (device dev/term) supported by POSIX. This corresponds to the number of POSIX accesses via BS2000 dialog tasks (START-POSIX-SHELL command).
PORTMON	Switch on/off port monitoring for NFS (0=off, 1=on).