IPL ( INITIAL PROGRAM LOAD)

TYPES OF IPL:

COLD START: Purge the spool and load PLPA
WORM START : Use the previous data , no PLPA
QUICK START: purge the spool and no PLPA

PLPA: pageable link package area
This area contains SVC routines, access methods, and other READ-ONLY System Programs, along with any READ-ONLY reenterable user programs selected by an installation that can be shared among users of the system.

Process in IPL:

1.Hardware reset
2.Memory clear ( optional)
3.Issue a basic read command to IPL devices ,it reads the records (cyl 0,trk 0 )
4.Start reading the IO devices from record 2.
5.If IO devices are read successfully , it loads PSW (program status word) from location 0.

IPL PARAMETER:

During IPL the system looks for the LOADxx in the following order.
(LOADXX  : information about IO configuration ad master catalog)

1.SYS0.IPLPARM to SYS9.IPLPARM in IODF
2.SYS1.PARMLIB in IODF
3.SYS1.PARMLIB in SYS VOLUME..

IPL FLOW:


1. Stop batch process  ---> $P XEQ

2. Stop printing ---> $P PRT

3. Notify the online users ---> SE " MESSAGE "

4.Stop online systems ---> $P TSO

5.Stop TELNET ---> STOP TN3270

6.Stop TCP/IP ---> STOP TCPIP

7.Stop DB2 ---> -DB01 STOP DB

8. Stop VTAM ---> ZNET CANCEL

9. Purge the Initiator ---> $P INIT

10. Stop JES2 ---> $ JES2.

RELOAD 

1.VARY CN(*),ACTIVATE (Note: after this command only OS starts communicate with  the user)

2.COLD START --->NOREQ,COLD ( Starts VTAM,TELNET and TCP/IP0

3.Start DB2 ---> -DB01 START DB2

4.Start CICS SUBSYSTEM ---> $S KEONCICS ( KEON is our training LPAR).

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