Cics data access-session 4
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The document discusses CICS file handling concepts, focusing on VSAM file types and their associated control commands, including random and sequential access, as well as error processing. It explains how to read, write, update, and delete records from VSAM files and highlights the commands used for browsing records. Additionally, it touches on the integration of CICS with DB2 and IMS databases, emphasizing the program preparation and improved performance through virtual storage.
![VSAM - READ from File :
Syntax
EXEC CICS READ DATASET(file-name)
INTO (rec-area)
LENGTH(record_length)]
RIDFLD(key-value)
RBA | RRN]
GENERIC]
KEYLENGTH(key-length)]
[UPDATE]
[GTEQ | EQUAL]
END-EXEC.](https://image.slidesharecdn.com/cics-dataaccess-session4-170702133020/85/Cics-data-access-session-4-14-320.jpg)
![VSAM – Write to File : Syntax
EXEC CICS WRITE
DATASET(file-name)
FROM(file-rec)
LENGTH(rec-length)
RIDFLD(rec-key)
[RBA | RRN]
END-EXEC.](https://image.slidesharecdn.com/cics-dataaccess-session4-170702133020/85/Cics-data-access-session-4-17-320.jpg)
![VSAM - Delete From File :
Syntax
EXEC CICS DELETE
DATASET (file-name)
RIDFLD(rec-key)
[KEY-LENGTH(key-length)]
[GENERIC[NUMREC(rec-number)]]
[RBA | RRN]
END-EXEC.](https://image.slidesharecdn.com/cics-dataaccess-session4-170702133020/85/Cics-data-access-session-4-20-320.jpg)
Cics data access-session 4
- 1. CICS - DATA ACCESS DAY 2 - SESSION 4 Updated in Nov 2004
- 2. Session 4 : ObjectivesTo Understand CICS File handling Concepts VSAM file types supported VSAM File control Commands VSAM File Browse Commands Exceptions in File Handling CICS-Database access : DB2 & IMS/DB
- 5. CICS – VSAM File Handling Supports VSAM ◦ BDAM supported in earlier versions of CICS Files to be defined to CICS as resources in the FCT File Opening, Closing done by CICS Provides interface for ◦ Random access ◦ Sequential access ◦ Read, Write, Update, Delete
- 6. File Access Methods - VSAM VSAM is the primary data access method for CICS VSAM file types supported ◦ Key Sequenced Data Set (KSDS) ◦ Entry Sequenced Data Set (ESDS) ◦ Relative Record Data Set (RRDS)
- 7. Entry Sequenced Data Set (ESDS) Records to be entered into the data set VSAM ESDS
- 8. ESDS - Relative Byte Address 100 BYTES REC1 200 BYTES REC2 300 BYTES REC3 0 100 200 RBA of REC3 is 200
- 9. Key Sequenced Data Set (KSDS) 60 40 Key Field 20 25 58 63 Records For Insert
- 10. Relative Record Data Set (RRDS) REC3 REC1 REC2 REC5 REC3 SLOT 1 SLOT 2 SLOT 3 SLOT 4 SLOT 5
- 11. Record identification (RIDFLD) RECORD KEY PARTIAL KEY RELATIVE BYTE ADDRESS (RBA) RELATIVE RECORD NUMBER (RRN)
- 12. VSAM File – Random Access Random Access READ WRITE a new record REWRITE a record previously ‘read for update’ DELETE UNLOCK a record previously ‘read for update’
- 13. VSAM File – Sequential AccessSequential Read (Browsing) Start Browsing Read Next Read Previous End Browsing Reset Browsing conditions
- 14. VSAM - READ from File : Syntax EXEC CICS READ DATASET(file-name) INTO (rec-area) LENGTH(record_length)] RIDFLD(key-value) RBA | RRN] GENERIC] KEYLENGTH(key-length)] [UPDATE] [GTEQ | EQUAL] END-EXEC.
- 15. VSAM - READ from FILE : Example WORKING- STORAGE SECTION. 77 WS-REC-LEN PIC S9(4) COMP. 77 WS-FILE-NAME PIC X(8) VALUE ‘ACCTMSTR’ 01 WS-FILE-REC 05 WS-REC-KEY PIC X(6). 05 WS-REC-DATA PIC X(34). PROCEDURE DIVISION. MOVE 40 TO WS-REC-LEN. MOVE ‘ABC451’ TO WS-REC-KEY. EXEC CICS READ DATASET(WS-FILE-NAME) INTO (WS-FILE-REC) RIDFLD(WS-REC-KEY) LENGTH(WS-REC-LEN) END-EXEC.
- 16. VSAM – Steps to Add New Records WRITE NEW RECORD SET UP DATA VALUES FOR NEW RECORD MOVE KEY VALUE TO RID FIELD
- 17. VSAM – Write to File : Syntax EXEC CICS WRITE DATASET(file-name) FROM(file-rec) LENGTH(rec-length) RIDFLD(rec-key) [RBA | RRN] END-EXEC.
- 18. VSAM - File Update : Syntax EXEC CICS REWRITE DATASET (file-name) FROM (data-area) [LENGTH (rec-len) END EXEC.
- 19. VSAM – File UnlockTo release a record previously read for update EXEC CICS UNLOCK FILE / DATASET (name) END-EXEC.
- 20. VSAM - Delete From File : Syntax EXEC CICS DELETE DATASET (file-name) RIDFLD(rec-key) [KEY-LENGTH(key-length)] [GENERIC[NUMREC(rec-number)]] [RBA | RRN] END-EXEC.
- 21. VSAM - BROWSE Operation ESTABLISH START POSITION RETRIEVE NEXT RECORD PROCESS RECORD? TERMINATE BROWSE END OF BROWSE? PROCESS CHANGE POSITION YES YES YES NO NO NO
- 22. VSAM - BROWSE CommandsSTARTBR - Establish starting position within file READNEXT - Retrieve records in ascending order sequentially as set by STARTBR READPREV - Retrieve Records in descending (reverse) order as set by STARTBR RESETBR - Restart Browse by re-positioning the pointer ENDBR - Terminate Browse
- 23. VSAM - BROWSE : Example MOVE ‘VALUE’ TO KEY-REC EXEC CICS STARTBR FILE(‘FILEA’) RIDFLD(RECKEY) RESP(ERR-CODE) END-EXEC. IF ERR-CODE = DFHRESP(NORMAL) PERFORM UNTIL ERR-CODE = DFHRESP(ENDFILE). PERFORM 2000-REC-FROM-FILE UNTIL 2000-REC-FROM-FIL-EXIT EXEC CICS READNEXT FILE(‘FILEA’) INTO(FILEREC) RIDFLD(RECKEY) RESP(ERR-CODE) END-EXEC END-PERFORM EXEC CICS ENDBR FILE(‘FILEA’) …. END-EXEC ELSE PERFORM 9000-HANDLE-ERROR ….. END-IF.
- 24. File Handling - Exceptional Conditions Processing Information ◦ NOTFND ◦ ENDFILE ◦ LENGERR Application Program Error ◦ INVREQ ◦ FILENOTFOUND ◦ ILLOGIC ◦ DUPREC External Conditions ◦ IOERR ◦ DISABLED ◦ NOTOPEN ◦ NOSPACE
- 25. File Handling - Program Organization WORKING STORAGE RECORD LAYOUT DEFINITION RECORD ID FIELD LINKAGE SECTION EIB PROCEDURE DIVISION IDENTIFY KEY OF THE RECORD TO BE READ EXEC CICS READ FILE....
- 26. CICS - Database Access Provides Interface to ◦Hierarchical Database - IMS/DB ◦Relational Database - DB2
- 27. DB2 Database Access from CICS Terminal Users CICS subsystem CICS subsystem Terminal Control & BMS modules CICS - DB2 Attachment Facility Modules DB2 Sub system Appl. pgm1 Appl. pgm2 Appl. pgm3 Threads Tables, Files Stored on disk Other CICS Modules
- 28. CICS - DB2 Program Preparation Compile Object Module Link-Edit Load Module Compiler Listing Translated Source Source Program Translator Listing Translate Precompile Listing Pre-Compile Application Plan DBRM Bind
- 29. Files - Data Tables New feature of storing VSAM files in virtual storage Improved performance ◦ User Maintained Table(UMT) ◦ CICS Maintained Table (CMT) ◦ Shared Data Tables Transparent to application program
- 30. Session 4 : Summary CICS File handling - use of FCT VSAM file types Supported - Random Access & Sequential Read File control commands - READ, WRITE, REWRITE, DELETE Browse commands – STARTBR, READNEXT, READPREV, RESETBR, ENDBR Exceptional Conditions in File Handling CICS-DB2 program preparation; RCT entries