1. Overview IPL is booting the system An initial program load
(IPL) is the act of loading acopy of the operating system from disk
into theprocessors real storage and executing it..2
2. IPLing the machineLOADPARMbootstrapIPL ccuuISYSRESIPLtextIODF
ccuu LOADxx IMSIAltNuc1 - 4 5 - 6 7 8IPL3 3. 4 4. 5 5. 6 6. LOADxx7
7. 8 8. 9 9. 10 10. Initialization Process Not all disks attached
to a CPU have loadable code on them. A disk thatdoes is generally
referred to as an IPLable disk, and more specificallyas the SYSRES
volume IPLable disks contain a bootstrap module at cylinder 0 track
0. Once system is loaded from HMC, this bootstrap is loaded into
storageat real address zero and control is passed to it. The
bootstrap then reads the IPL control program IEAIPL00/IPLTEXTand
passes control to it. This in turn starts the more complex task
ofloading the operating system and executing it.11 11. After the
bootstrap is loaded and control is passed to IEAIPL00, itprepares
an environment suitable for starting the programs andmodules that
make up the operating system, as follows: Clears central storage to
zeros Locates the SYS1.NUCLEUS data set on the SYSRES volume and
loads aseries of programs from it known as IPL Resource
InitializationModules (IRIMs). IRIMs begin creating the normal
operating system environment ofcontrol blocks and subsystems.12 12.
IRIM Functions Read the LOADPARM information entered on the
hardware console atthe time the IPL command was executed. IRIM will
first attempt to locate LOADxx in SYS0.IPLPARM &continues till
SYS1.PARMLIB Get the information from LOADxx including the nucleus
suffix, themaster catalog name, and the suffix of the IEASYSxx
member to beused, is read from it. Load the operating systems
nucleus & initialize virtual storage inmaster scheduler address
space for SQA13 13. Initialize real storage management, including
the segment table for themaster scheduler, segment table entries
for common storage areas, andthe page frame table. At last of the
IRIMs then loads the first part of the NucleusInitialization
Program (NIP), which invokes the Resource Initialization
Modules(RIMs), one of the earliest of which starts up
communications with theNIP console defined in the IODF.14 14. NIP
Functions Expands the SQA and the extended SQA by the amounts
specified on the SQAsystem parameter. Creates the pageable link
pack area (PLPA) and the extended PLPA for a coldstart IPL Loads
modules into the fixed link pack area (FLPA) Loads modules into the
modified link pack area (MLPA) Allocates virtual storage for the
common service area (CSA)15 15. System address space creation In
addition to initializing system areas, z/OS establishessystem
component address spaces. It establishes an addressspace for the
master scheduler and other system addressspaces for various
subsystems and system components. Some of the component address
spaces are: *MASTER*,ALLOCAS, APPC, CATALOG, and so on.16 16.
Master scheduler initialization Master scheduler initialization
routines initialize systemservices such as the system log and
communications task,and start the master scheduler itself. They
also causecreation of the system address space for the job
entrysubsystem (JES2 or JES3), and then start the job
entrysubsystem.17 17. Subsystem initialization Subsystem
initialization is the process of readying asubsystem for use in the
system. IEFSSNxx members of SYS1.PARMLIB contain thedefinitions for
the primary subsystems such as JES2 or JES3,and the secondary
subsystems such as NetView and DB2.18 18. Virtual Storage Layout
for Multiple Address SpacesStarted Tasks*MASTER*PCAUTHRASPTRACE. .
.CATALOGCONSOLEALLOCASVLFLLAJESVTAMCICSTSOTSOUSERINIT/JOBBatchJobTSOLOGONSystem
andSubsystemAddress SpacesSMS19 19. The 31-bit address space016
MB16MExtendedPrivateELSQA/ESWA/229/230/249Extended User
RegionExtendedCommonCommonPrivateCommonExtended CSAExtended
PLPA/FLPA/MLPAExtended SQAExtended
NucleusNucleusSQAPLPA/FLPA/MLPACSALSQA/SWA/229/230/249User
RegionSystem RegionPSA20KB4KB20 20. 21IPL WTORsIf you receive the
message IEA888A for the clock, enter:=> r 00,uIf you receive the
message IXCZ48E for XCF data sets, enter:=> r 00,uWhen the
$HASP426 SPECIFY OPTIONS message appears, enter the following
tocold start JES2:=> xx COLD,NOREQwhere xx is the reply ID of
the console prompt. 21. IPL Types Cold start: PLPA is reloaded and
VIO is cleared. This must happenwhen the contents of LPA have
changed Quick Start: PLPA is not reloaded but VIO is cleared. No
changes weremade to LPA but VIO needs to be refreshed Warm Start:
PLPA and VIO are retained from before the IPL allowingjobs to
restart using journal VIO data Note: VIO is a method of using
memory to store small temporary data sets for rapidaccess.22 22.
System shutdown z/OS systems are designed to run continuously with
potentially manymonths between reloads Systems are only shutdown
when necessary usually for a change Each task needs to be shut down
in the correct order Usually this is done by an automation package
The final commands to remove automation and remove connections
toother systems are performed by the operators23 23. SYSTEM
PARMLIBs24 24. PROGxx25 25. 26Issue following command to
dynamically activate above linklistchanges.SET PROG=89 26.
TSOKEYxx27 27. MSTJCL0028 28. LPALSTxx29 29. IEASYMxx30 30.
IEFSSNxx31 31. IEAFIXxx32 32. IEALPAxx33 33. CLOCKxx34 34.
COMMNDxx35 35. JES2PARM36 36. BPXPRMxx37 37. SMFPRMxx38 38.
CONSOLxx39 39. Commands40 40. 41 41. Thank You 42
