This document describes purpose and usage of a Natural Global Buffer Pool (GBP) under the operating system z/OS.
The following topics are covered:
Certain parts of the Natural global buffer pool are identical under z/OS and z/VSE. These parts are concentrated in a separate section (see Common GBP Operating Functions under z/OS and z/VSE) which covers the following topics:
See also:
Natural Global Buffer Pool Manager Messages in the Natural Messages and Codes documentation
The Natural global buffer pool is a segment of storage assigned from the z/OS extended common system area (ECSA) above 16 MB (or from CSA storage below, if requested), used by Natural to load and execute Natural programs.
Using a global buffer pool, multiple Natural sessions under different TP monitors (multiple copies of CICS, TSO, IMS TM, etc.) and/or in multiple batch sessions share the same area - thus requiring less storage than would be required for a local buffer pool in each environment.
The following topics are covered below:
Note:
vrs stands for version, release and
system maintenance level of the product.
The global buffer pool is operated by the program
NATGBPvr which must be executed from an
authorized library.
During the installation of Natural, the modules
NATGBPvr is linked into an
APF-authorized library.
If the z/OS parameter ALLOWUSERKEYCSA(YES) has explicitly
been specified in SYS1.PARMLIB(DIAGxx),
a Natural global buffer pool is allocated in user key, so that Natural sessions
accessing a global buffer pool have write permission for that buffer pool.
If ALLOWUSERKEYCSA(NO) is in effect, a Natural global buffer pool is allocated in system key; therefore, Natural
sessions accessing a global buffer pool do not have any write permission for that buffer pool. These Natural
sessions call the Authorized Services Manager (ASM) to perform all buffer pool functions. As a consequence, installation of
the Authorized Services
Manager is mandatory. The
Authorized Services Mangager ist not only called to load a Natural object into the buffer pool but also to
maintain the use count of a Natural object if the execution of this Natural object is started or terminated. The
calls to the Authorized Services Manager will increase Natural’s resource consumption. The overhead is hard to
predict and depends on the application profile (ratio of programm calls to program execution time).
The functions available from
NATGBPvr are activated in that they
are
provided by a parameter card (PARM=),
read from a file (see below)
or supplied by the MODIFY operator command
unless NATGBPvr has not been
terminated.
NATGBPvr expects the first
command in the parameter field (PARM=) of the
EXEC statement.
You may enter:
one of the functions (described in the section Common GBP Operating Functions under z/OS and z/VSE)
or a reference to an input file with
CF=<dd-name>, where
<dd-name> represents a DD name
defined in the JCL. Only "card image" files are supported, that
is, RECFM=F,LRECL=80, and only the first 72 bytes of the input
record are honored. Every record included from the input file represents a
command. Blank records or records prefixed with an asterisk (*) are ignored. A
file is processed until End-Of-File (EOF). Example:
PARM='CF=SYSIN1'
If the parameter field is not supplied or blank, the commands will be
read from file SYSIN by default.
It is only possible to enter one function at a time at the console or one function per line using the command file, otherwise an error message will be returned.
Each command received, from the parameter card, from file input or from operator console input is shown on the operator console.
To start program NATGBPvr,
either start a started task or submit a job, which executes
NATGBPvr.
Important:
To ensure that the global buffer pool is retained after a
system failure, the global buffer pool should be started automatically during
machine IPL.
After all commands are processed,
NATGBPvr terminates, unless
RESIDENT=Y was
specified
or a buffer pool with a cache was created.
NATGBPvr will return one of the
following condition codes:
| 0 | All functions executed successfully. |
| 20 | An error has occurred; see the message log for details. |
The following examples show sample batch jobs for creating and terminating a global buffer pool.
In the following examples, the notation vrs or vr stands for the relevant version, release, system maintenance level numbers. For further information on product versions, see Version in the Glossary.
//GBPSTART JOB //* //* Starts a global buffer pool with the name NATvrGBP, a size of 1 MB and //* a text block size of 4 KB. The global buffer pool is allocated above 16 MB. //* The subsystem used is NATv. //* After the allocation, the job GBPSTART terminates. //* //STEP EXEC PGM=NATGBPvr,PARM='BPN=NATvrGBP,N=(1M)' //SETPLIB DD DISP=SHR,DSN=USER.APF.LINKLIB
//GBPRES JOB //* //* Starts a global buffer pool with the name GBP, a default size of //* 100 KB and a text block size of 1 KB. The global buffer pool is allocated //* below 16 MB. The subsystem used is SAGS. //* After the allocation, the job GBPRES will wait for further commands. //* Further commands may be entered using the MODIFY operator command: //* F GBPRES,command-string //* //STEP EXEC PGM=NATGBPvr,PARM='BPN=GBP,N=(,BL,1),S=SAGS,R=Y'
//GBPSTOP //* //* Stops the global buffer pool GPB if it contains no active objects. If it //* does contain active objects, the operator console will prompt for a reply. //* Depending on the reply, the shutdown will be forced (Y) or aborted (N). //* The subsystem used is NATv. //* //STEP EXEC PGM=NATGBPvr,PARM='FSHUT,BPN=GPB'
//GBPSTRT2 //* Read commands from SYSIN1: //* //* Start 3 global buffer pools (subsystem ID Nvrs) with name //* NATGBP1 - size=1024KB and a cache with size 2048KB //* NATGBP2 - size=2048KB without cache //* Display all buffer pools of subsystem ID "Nvrs". //* //* Note: The job does not terminate by itself, but stays resident and waits //* for operator commands, because it owns the data space allocated for //* buffer pool NATGBP1. //* //* If the buffer pools should shut down, send operator command MODIFY with //* parameter "CF=SYSIN2" to execute the corresponding FSHUTs. //* //STEP EXEC PGM=NATGBPvr,PARM='CF=SYSIN1' //SYSIN1 DD * CREATE,BPN=NATGBP1,S=Nvrs,N=(1M),BPC=2M CREATE,BPN=NATGBP2,S=Nvrs,N=(2M) SHOWBP S=Nvrs //SYSIN2 DD * FSHUT,BPN=NATGBP1,S=Nvrs FSHUT,BPN=NATGBP2,S=Nvrs SHOWBP S=Nvrs //*
The module NATGBPTX is delivered in source form. It
contains all error messages in English in mixed case. The messages can be
translated into other languages as required. In this case, the
"new" NATGBPTX source module has to be assembled and
NATGBPvr has to be relinked.
To issue the global buffer pool messages including their variable parts
in upper case, the global buffer pool parameter module NATGBPRM
has to be assembled with the UCTRAN parameter set to
YES, and NATGBPvr has to
be relinked.
To relink NATGBPvr, use the
following JCL:
//SYSLIN DD * SETCODE AC(1) SETOPT PARM(REUS=RENT) INCLUDE NATLIB(NATGBPMG) INCLUDE SMALIB(NATGBPRM) INCLUDE SMALIB(NATGBPTX) INCLUDE NATLIB(NATBPMGR) NAME NATGBPvr(R) /*
