INTRODUCTION TO MAINFRAME DATABASE
INTRODUCTION TO IMS-DB & DC
MPP , BMP , DLI
DBD, PSB, PCB
SEGMENT , FILEDS
ROOT PARENT - FIELDS
========================================================================

INTRODUCTION TO MAINFRAME DATABASE:

 MAINFRAME IS A COMPUTER 
	USED TO STORE & PROCESS HUGE AMOUNT DATA.
SO IF I WANT TO STORE THE DATA IN MAINFRAME == 2 PLACE

	1. FILE SYSTEM  --> 3 TYPES:
					1. QSAM --> PS
					2. VSAM --> KSDS
					3. GSAM --> IMS**  (LIKE PS BUT NOT PS)

	2. DATABASE	--> 3 TYPES
					1. NETWORK --> IDMS (OLD - FEW PROJECT)
					2. HI-RE	IMS (GOOD NUM OF PROJECT)
					3. RELATIONAL	DB2 -- ALL PROJECT

 IMS & DB2 == PRODUCT OF IBM

  --> IBM - IMS (1ST DATABASE)
	->  Database2 -- DB2	== 


 IMS -->  2 TYPES	1. IMS-DB	--> STORE THE DATA
			2. IMS-DC	--> WAY TO COMMUNICATE THE DATA --/ ONLINE APPLICATION.


	CICS --> ONLINE APPLICATION..

		DB-DC SYSTEM --> DB - STORE
				DC - COMMUNICATION --> USE THIS ONE

	IMS --> DB-DC  ==> DB - STORE
			  DC - COMMUNICATE --> MFS


  >> SEEING A COBOL PGM , HOW CAN U TELL WHAT TYPE OF PGM IT IS:

	ONLY COBOL --> MAINPGM	--> CALL   (  A - B - C) --> 1. EXECUTED BY JCL  ( //STEP1 EXEC PGM=MAINPGM )
			SUBPGM	 --> LINKAGE SECTION  <=> PROCEDURE DIVISION  <=> EXIT PROGRAM

	COBOL-FILE  -->		ENVIRONMENT DIVISION

	COBOL-DB2   --> 	EXEC SQL 

	COBOL-IMS   ----> 	LINKAGE SECTION
					PCB
				PROCEDURE DIVISION USING PCB**
				 F 'CBLTDLI'

	COBOL-CICS  --. 	EXEC CICS

 IMS - 3 TYPES OF PGM	
		1. MPP	--> ONLINE 
		2. DLI  --> BATCH
		3. BMP  --> BOTH

-- IF U WANT WORK ON IMS -- 

1. DBD	-- PHSYCIAL STRUCT.. -COLLECTION OF SEG
		CONTAINS --> SEGEMENT 	 -->   TABLES
			CONTAINS --> FILEDS  ==?>  DB2 COLUMNS

	ORGANIZATION DATABASE
	
		ORG-SEG		-- IBM,TCS				== ROOT SEGMENT (0)

	CLIENT-SEG (AMEX)-GOVT		 EMPLOYEE			== CHILD/ PARENT

	PROJECT SEG(BILL SYSTEM),A,B	 SALARY				-- CHILD
	

	IN OUR -> AUTOMOBILE --> ORDER DB
				 PRODUCT DB  -- LOCATION, PRICE , INVENTORY
				 BUYER/DEALER DB

2. PSB  - LOICAL STRUCT  -- USED TO ACCESS THE SEG BY PGM..

	VIEW -DB2 
	PSB  -- ACCESS TO SEG THAT CAN BE USECD IN COBOL-IMS PGM	
	
	PSB -- COLLECTION OF PCBS 


3. PCB  -- TO TELL WHAT SEGMENT , FILEDS CAN BE ACCESSED BY THE PGM..


 IMS -DB-DC  == STORE & COMMUNICATE.

	1. DBD
	2. PSB -PCB


HOW TO RESOLVE A SPACE ABEND:-  	1. INCREASE THE SPACE
						> HOW MUCH SPACE
					2. AFTER INCREASE AND RERUN THE JOB ABEND AGAIN
						> WHAT U WILL DO