This document provides a summary of those operating functions of the Natural global buffer pool which are identical under z/OS and z/VSE.
The following topics are covered:
The global buffer pool parameter module NATGBPRM is used to
set global processing options which apply to all functions and buffer pools.
The global buffer pool parameter module is delivered in source and object form
with all defaults set.
The following parameter is available:
This parameter enables or disables the lower/mixed case support for the global buffer pool messages.
UCTRAN=NO |
Lower/mixed case support is fully enabled.
This is the default value. |
UCTRAN=YES |
All global buffer pool messages are issued in upper case. |
The following functions are available:
Note:
If no function is specified,
CREATE
is assumed when the profile parameter BPNAME is
specified, otherwise
NOP
is assumed.
This function adds cache storage to an existing global buffer pool.
This function creates a global buffer pool with the specified parameters.
This function removes the cache storage of a global buffer pool without shutting down the buffer pool itself.
The global buffer pool is shut down, and the storage area is released.
If there are no active objects in the buffer pool,
FSHUT is executed immediately.
If there are still active objects in the buffer pool, this will be
indicated to the operator. Depending on the setting of the parameter
CONFIRM,
the operator is asked for a confirmation or FSHUT is
executed immediately.
This function shows all global parameter settings, that is, parameters which do not only apply to the statement for which they have been specified.
In addition, the storage key of the global buffer pool(s) is shown.
This function lists all global buffer pool caches currently owned by the job.
This function code particularly can be used to set global parameters.
With the REFRESH command it is possible to
re-initialize an already active buffer pool. As no storage allocation takes
place, the buffer pool size and location (above or below 16 MB) remain
unchanged. However, it is possible to change the text-block size (see
NATBUFFER
parameter).
You should use this function only if the Current Use Count (see Fields for Buffer Pool Objects in SYSBPM Directory Information) is equal to zero (see warning below) or if the buffer pool has been destroyed.
 |
Warning: If you re-initialize the buffer pool while Natural objects are being executed by active sessions in this buffer pool, the results of the active sessions are unpredictable and Natural may even abend. |
Displays all buffer pools currently existing.
The GBP operating program is terminated. This termination does not affect any active global buffer pool.
Displays all Zaps applied to the global buffer pool operating program.
The functions of the Natural GBP operating program can be controlled with the aid of parameters. These parameters can be specified in any sequence. They can be abbreviated so that they are still unique.
Note:
If you like to start multiple global buffer pools with an associated
cache, you are recommended to use a single job or (under z/OS only) a single
started task and to supply the different
CREATE
commands in an input dataset. See Example 4 in the section Natural
Global Buffer Pool under z/OS or Example 4 in the section Natural
Global Buffer Pool under z/VSE.
The following parameters are available:
This parameter is mandatory (except for the
TERMINATE
function). It specifies the name of the global buffer pool to be created.
BPNAME=name |
name is the 8-byte
name of the global buffer pool. If the specified name is shorter than 8 bytes,
blanks will be appended to it.
|
For the functions
DELCACHE
and FSHUT,
you may supply a value of "*" to process all buffer
pools for the specified Natural subsystem.
This parameter specifies the name of the preload list.
BPLIST=name |
name is the 8-byte
name of the preload list. If the specified name is shorter than 8 bytes, blanks
will be appended to it.
|
This parameter specifies the amount of storage (in KB) used to allocate a data space for the buffer pool cache.
BPCSIZE=size
|
The cache size can also be specified in units of MB or GB, e.g. by specifying 10M for 10 MB. If the BPCSIZE parameter is omitted (or set to zero), the buffer pool is not supplied with a cache. Note: |
This parameter controls the
FSHUT
behavior if there are still active objects in the buffer pool.
CONFIRM=Y |
A confirmation for the FSHUT function is required
from the operator. The operator can decide to abort or to force the
FSHUT function.
This is the default value. |
CONFIRM=N |
FSHUT is forced without interaction with the
operator.
|
This parameter is only valid for the
FSHUT
command it has been specified with, that is, CONFIRM has to be
specified with each FSHUT parameter, and it does not apply to
subsequent FSHUT commands.
This parameter is ignored when the task does not own a buffer pool cache.
IDLE=nn |
nn is the number of
seconds to elapse before the GBP operating program checks for each buffer pool
cache if its associated buffer pool is still active; if not that buffer pool
cache is released; when the last buffer pool cache owned by the task has been
released, the task terminates, unless RESIDENT=Y has been specified.
The default setting is 60 seconds. |
IDLE is a "global" parameter, i.e.
once specified, IDLE will also apply to subsequent
commands, without your having to specify it again.
Note:
Under z/OS, the GBP operating program also checks the specified
IDLE time value against the job's timeout value: the
specified IDLE time value internally may reduce IDLE to
prevent timeout abends (S322).
This parameter controls which algorithm is to be used for allocating storage in the Natural buffer pool.
METHOD=S |
Indicates that a selection process is to be used for allocating storage. The selection process consists of browsing the whole buffer pool directory and comparing different entries in order to find a most suitable entry. This method was formerly known as algorithm 1+2. This is the default value. |
METHOD=N |
Indicates that the next available unused or free space is to be used. The search for the next available space is done from a pointer to directory entries which moves in a wrap-around fashion. This method may be used in combination with a buffer pool cache. |
This parameter is only valid for the
CREATE
function. If you want to change the allocation method, restart the buffer
pool.
This parameter specifies the size and the mode of the buffer pool, and the text block size.
NATBUFFER=(size,mode,tsize)
|
size |
is the amount of storage (in KB) to be allocated. For the Natural buffer pool ( For the other buffer pools, the default and minimum possible size is 100 KB. The specified amount of storage is always rounded up to a multiple of 4 KB. The pool size can also be specified in units of MB or GB, e.g. by specifying 10M for 10 MB. Next to the storage specified by size, one page (4 KB) of write protected storage will be allocated for administrative purposes. |
mode |
determines if the global buffer pool is to be allocated above or below 16 MB. Possible values are: XA = above (default), BL = below. |
|
tsize |
determines the text block size (in KB). Possible values are: 1, 2, 4 ,8, 12, and 16. The default is 4. |
|
| size, mode and tsize have to be specified in the sequence shown above. | ||
If NATBUFFER is not specified, the default
values will be used. See also
Examples of
NATBUFFER Specifications below.
This parameter specifies the behavior of the GBP operating program after the specified function has been executed. The following values are possible:
RESIDENT=Y
|
The GBP operating program will remain active after executing
the specified function and await further commands. Once specified,
RESIDENT=Y will also apply to subsequent commands, without your
having to specify it again. (To stop the GBP operating program, you use the
TERMINATE
function.)
|
RESIDENT=N |
The GBP operating program will terminate after executing the
specified function, if no further command is available. If the task owns a
buffer pool cache, RESIDENT=N is ignored and the task is not
terminated.
|
RESIDENT=A |
The GBP operating program automatically decides how to behave
after having processed all commands. It will terminate if
In other words: If no buffer pool cache is owned by the task,
This is the default setting. |
RESIDENT is a "global" parameter,
i.e. once specified, RESIDENT will also apply to
subsequent commands until explicitely specified/overwritten.
This parameter specifies the ID of the Natural subsystem.
SUBSID=id |
Once specified, The default value is NATv, where
|
SUBSID is a "global" parameter,
that is, once specified, SUBSID will also apply to
subsequent commands until explicitely specified/overwritten.
For the functions
DELCACHE,
FSHUT
and
SHOWBP,
you may supply a value of "*" to process all buffer
pools for the specified Natural subsystem.
For further information on the Natural subsystem, see Natural Subsystem (z/OS) or Natural Subsystem (z/VSE).
This parameter specifies the type of the buffer pool. Possible values are:
The following examples refer to the
NATBUFFER
parameter which is used to set buffer size, mode and text block size, the
parameter name being abbreviated (N).
Example 1: To allocate a global buffer pool above 16 MB, with a size of 1 MB and a text block size of 1 KB, you specify:
N=(1000,,1)
or
N=(1M,,1)
Example 2: To allocate a global buffer pool above 16 MB, with a size of 10 MB and a text block size of 4 KB, you specify:
N=(10000)
or
N=(10M)
Example 3: To allocate a global buffer pool above 16 MB, with a size of 256 KB and a text block size of 4 KB, you specify:
N=(,,)
This is equivalent to omitting the
NATBUFFER
parameter altogether, as it causes the default values to apply.
