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Enterprise COBOL Concepts

Enterprise COBOL Concepts. Dr. David Woolbright woolbright_david@columbusstate.edu 2013. Video Link. Watch the Introductory video lesson here. COBOL?. Co mmon B usiness O riented L anguage Billions of lines of existing code with more added each year Designed for business processing

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Enterprise COBOL Concepts

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  1. Enterprise COBOL Concepts Dr. David Woolbright woolbright_david@columbusstate.edu 2013

  2. Video Link • Watch the Introductory video lesson here

  3. COBOL? • Common Business Oriented Language • Billions of lines of existing code with more added each year • Designed for business processing • Great compilers • Cobol programs execute quickly • Relatively simple to learn • Not your father’s or mother’s COBOL - The language keeps evolving (XML, OO)

  4. Enterprise Cobol for z\OS IBM COBOL: • http://www-01.ibm.com/software/awdtools/cobol/zos/ Languagage Reference • http://publibfp.boulder.ibm.com/epubs/pdf/igy3lr50.pdf Programming Guide • http://publibfp.boulder.ibm.com/epubs/pdf/igy3pg50.pdf

  5. Program Organization • Program – Organized like a book • Division – Identification, Environment, Data, Procedure • Section • Paragraph • Sentence • Clause • Phrase • Word

  6. Grammatical Hierarchy • The grammatical hierarchy follows this form: • Identification division • Paragraphs • Entries • Clauses • Environment division • Sections • Paragraphs • Entries • Clauses • Phrases • Data division • Sections • Entries • Clauses • Phrases • Procedure division • Sections • Paragraphs • Sentences • Statements • Phrases

  7. Coding Rules • Cols 1-6 – left blank. Editor fills in with sequence numbers • Col 7 – Usually blank,* means comment line, - is continuation, D for debugging lines • Cols 8-11 – “A” margin or Area A • Cols 12-72 – “B” margin or Area B • Cols 73-80 – unused • 1 2 3 4 5 6|7| 8 9 10 11|12 13 …71 72 | Seq Nos | | Area A | Area B |

  8. Continuation of Statements • Statements can be continued on the next line in Area B

  9. Continuation of Literals • Continue the constant through column 71 • Put a “-” in column 7 • Continue constant with a ‘ OR “ • Continue constant in area B

  10. Things That Go in Area A Area A items: • Division headers • Section headers • Paragraph headers or paragraph names • Level indicators or level-numbers (01 and 77) • DECLARATIVES and END DECLARATIVES • End program, end class, and end method markers

  11. Things That Go in Area B Area B items: • Entries, sentences, statements, and clauses • Continuation lines

  12. Things That Go in A or B • Level-numbers • Comment lines • Compiler-directing statements • Debugging lines • Pseudo-text

  13. Preparing a Program Your Cobol Program Object Module Load Module CoboL Compiler Linkage Editor

  14. Things You Should Try • You will need to create a PDS (Partitioned Data Set) to hold the programs (members) you create. You can watch a video about how to create a PDS here. • You will also need a load library where the linkage editor can place the executable programs (load modules) you create. Here is a video that describes how to build a load library.

  15. Things You Should Try • When you’re beginning to learn a new language, it’s a good idea to type in a few programs from scratch. Here is a Hello, World program you should create in your PDS. And here is a video of how to create the program. • Here’s a link to some JCL that can be modified to compile, link, and run a COBOL program on your system.

  16. Things You Should Try • Here is a video that discusses how to change the JCL to fit your situation.

  17. Video Link • Watch the Video lesson #2 here

  18. Structure of a Program

  19. IDENTIFICATION DIVISION IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. AUTHOR. JOE SMITH. INSTALLATION. TSYS. DATE-WRITTEN. 12/03/2011. DATE-COMPILED. 12/03/2011. • Only PROGRAM-ID is required • Some interesting parms can be coded on the PROGRAM-ID

  20. ENVIRONMENT DIVISION This division connects external DD file names with internal file names. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT MSTRFILE ASSIGN TO MSTRFILE SELECT CUSTOMER-FILE ASSIGN TO CUSTMAST ORGANIZATION IS INDEXED ACCESS MODE IS RANDOM RECORD KEY IS COSTOMER-KEY FILE STATUS IS CUSTOMER-FILE-STATUS. Internal File Name External DD File Name

  21. DATA DIVISION • Used to create variables and constant fields • Only three data types • numeric PIC 99999. • alphanumeric (text/string) PIC XXX. • alphabetic PIC AAA. • Level numbers indicate subordination of fields. Use levels 01-49 • Alphabetic is seldom used

  22. Level Numbers • Group item – a subdivided field • Elementary item – a non-subdivided field • 01 – Group or independent item • Higher numbers indicate subordinate fields

  23. Level Numbers • 66, 77, 88 have special significance • 66 – Used to rename (no longer used) • 77 – An independent item (choose 01) • 88 – Condition name

  24. Level Numbers 01 XXX. 05 YYY. 10 AAA PIC X. 10 BBB PIC X. 05 ZZZ PIC X(20). 77 AAA PIC 999V99.

  25. Condition Names • 01 TRAN-CODE PIC X. 88 GOOD VALUE ‘G’. 88 BAD VALUE ‘B’. 88 INDIFFERENT VALUE ‘I’. … SET GOOD TO TRUE … IF (GOOD) … Equivalent to MOVE ‘G’ TO TRAN-CODE Equivalent to IF TRAN-CODE = ‘G’

  26. Level 88

  27. Condition Names

  28. Picture Clauses • Picture clause values usually use 9, X, V, S, A • 9 – a decimal digit • X – any alphanumeric character • V – an implied decimal point • S – a sign • A – A-Z, and blank

  29. Picture Clauses • PIC 9(6) • PIC 9(6)V99 • PIC 999999V99 • PICTURE X(10) • PIC XXXXXXXXXX • PIC S9(4)V9(4) • PIC S9999V9999 • PIC 9(18)

  30. Numeric Edited Fields • XXXBXXBXXXX • 99/99/99 • ZZ,ZZZ.99DB • ***,***.99 • ----.99 • $$$9.99 • 99999.99

  31. USAGE Clause • Specifies the format in which data is stored in memory • Normally, the phrase “USAGE IS” is omitted 01 COST USAGE IS PACKED-DECIMAL PIC S9(5). 01 COST PACKED-DECIMAL PIC S9(5). 01 FIRST-NAME USAGE ISDISPLAY PIC X(20). 01 FIRST-NAME PIC X(20).

  32. DATA DIVISION We define data used in input-output operations. FILE SECTION. FD CUSTOMER-FILE. 01 CUSTOMER-MASTER. 05 CUST-NUM PIC 9(2). 05 CUST-FNAME PIC X(20). 05 CUST-LNAME PIC X(20). FD SALES-REPORT. 01 REPORT-AREA PIC X(132).

  33. Data Formats Older terms: Modern terms: • COMPUTATIONAL BINARY • COMP BINARY • COMP-1 FLOATING POINT • COMP-2 FLOATING POINT • COMP-3 PACKED-DECIMAL • COMP-4 BINARY • COMP-5 BINARY (NATIVE) 05 XDATA PIC S9(5) PACKED-DECIMAL. 05 YDATA PIC S9(4) BINARY.

  34. EBCDIC • EBCDIC is an IBM format for storing alphanumeric characters A - X’C1’ J - X’D1’ B - X’C2’ K - X’D2’ S – X’E2’ C - X’C3’ L - X’D3’ T – X’E3’ D - X’C4’ M - X’D4’ U – X’E4’ E - X’C5’ N - X’D5’ V – X’E5’ F - X’C6’ O - X’D6’ W – X’E6’ G - X’C7’ P - X’D7’ X – X’E7’ H - X’C8’ Q - X’D8’ Y – X’E8’ I - X’C9’ R - X’D9’ Z – X’E9’

  35. EBCDIC • EBCDIC is an IBM format for storing alphanumeric characters 0 - X’F0’ SPACE – X’40’ 1 – X’F1’ . - X’4B’ 2 - X’F2’ , - X’6B’ 3 – X’F3’ * - X’5C’ 4 - X’F4’ - - X’60’ 5 – X’F5’ 6 - X’F6’ 7 – X’F7’ 8 – X’F8’ 9 – X’F9’

  36. BINARY DATA • Stored in 2’s Complement format • Leftmost bit is a sign ( 0  +, 1  - ) • If the number is positive, interpret it as plain binary 01011 = 8 + 2 + 1 = + 11 • If the number is negative, compute the complement – Invert. (Change all 1’s to 0’s and 0’s to 1’s.) Add 1. The result is the additive complement

  37. BINARY DATA • 10011 is a negative number. Inverting we have 01100. Adding 1 we have 01100 + 1 = 01101. This is a positive number. 01101  8 + 4 + 1 = 13, so the original number is -13.

  38. BINARY DATA • Declaring a data field as BINARY causes the data to be stored in 2’s complement format. • 01 X-FIELD PIC S9(4) BINARY VALUE -1. • X-FIELD will contain 1111111111111111 = X’FFFF’. • Binary data is processed in a register

  39. PACKED-DECIMAL DATA • Defining a field to be PACKED-DECIMAL or Computational-3 causes the data to be stored internally in a packed decimal format. • There are 2 decimal digits stored in each byte. A sign is stored in the rightmost “nibble”. (C  +, D  -) • Y-FIELD PIC S999 VALUE -23 PACKED-DECIMAL. produces a 2 byte field containing X’023D’ • Most business arithmetic occurs in packed decimal.

  40. Packed No-Sign Data • Packed no-sign data is a non-native data type that was created to save space on a disk when storing dates • If the digits in a date like 10/23/89 were stored in a packed field, the field would require 4 bytes: 01|02|38|9C • By removing the sign, the date fits in 3 bytes: 10|23|89

  41. Packed No-Sign Data • These type fields require special handling in Cobol • Program PKNOSIGN illustrates how a displayable date can be recovered from a packed no-sign field.

  42. ZONED-DECIMAL DATA • A numeric field which is described as DISPLAY, or in which the usage clause is omitted, is stored in a zoned decimal format. • In zoned decimal, each digit takes up one byte, and a sign is stored in the zone portion of the rightmost byte of the field. • Z-FIELD PIC S999 VALUE -32 produces a 3 byte field containing X’F0F3D2’.

  43. ZONED-DECIMAL DATA • Z-FIELD PIC S999 VALUE -32. produces a 3 byte field containing X’F0F3D2’. • Z-FIELD PIC S999 VALUE 32. produces a 3 byte field containing X’F0F3C2’. • W-FIELD PIC 999 VALUE 0. MOVE -32 TO W-FIELD produces a 3 byte field containing X’F0F3C2’.

  44. DATA DIVISION Define the data needed for internal processing in the WORKING-STORAGE SECTION. Storage is statically allocated and exists for the life of the rununit. WORKING-STORAGE SECTION. 01 TOTAL-FIELDS. 05 CUST-TOTAL PIC S9(7)V99 VALUE 0. 05 COST-TOTAL PIC S9(7)V99 VALUE 0. 01 DATE-AND-TIME. 05 CD-YEAR PIC 9999. 05 CD-MONTH PIC 99.

  45. DATA RELATIONSHIPS BINARY PACKED-DECIMAL CHARACTER or ALPHANUMERIC ZONED-DECIMAL

  46. DATA DIVISION • Describe data that exists in another program, or storage you want to associate with a symbolic name in the LINKAGE SECTION. LINKAGE SECTION. 01 LK-DATA-AREA 05 NAME PIC X(40). 05 AGE PIC 999.

  47. DATA DIVISION The LOCAL-STORAGE SECTION is used to have storage allocated each time a program is entered, and deallocated on return from the program. Used for compatibility with C or Java. LOCAL-STORAGE SECTION. 01 CUST-NO PIC X(3). 01 COST PIC 9(5)V99.

  48. Initialization of Storage • WORKING-STORAGE for programs is allocated at the start of the run unit. • Any data items with VALUE clauses are initialized to the appropriate value at that time.

  49. Initialization of Storage • For the duration of the run unit, WORKING-STORAGE items persist in their last-used state. Exceptions are: 1) A program with INITIAL specified in the PROGRAM-ID paragraph In this case, WORKING-STORAGE data items are reinitialized each time the program is entered. IDENTIFICATION DIVISION. PROGRAM-ID. MAIN IS INITIAL. ...

  50. Initialization of Storage • For the duration of the run unit, WORKING-STORAGE items persist in their last-used state. Exceptions are: 2) A subprogram that is dynamically called and then canceled In this case, WORKING-STORAGE data items are reinitialized on the first reentry into the program following the CANCEL. MOVE ‘PROG23’ TO PROGID CALL PROGID CANCEL PROGID CALL PROGID

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