Mainframe Tips for Developers

COBOL Code Optimization

2012-03-21T15:08:00.000+05:30

To assist in the optimization of the code, you should use the OPTIMIZE compiler option. With theOPTIMIZE(STD) or OPTIMIZE(FULL) options in effect, you may receive optimizations that include: eliminating unnecessary branches simplifying inefficient branches simplifying the code for the out-of-line PERFORM statement, moving the performed paragraphs in-line,where possible simplifying the code for a

ARITH Compiler Option

2012-03-21T14:08:00.000+05:30

ARITH affects the maximum number of digits that you can code for integers, and the number of digits used in fixed-point intermediate results. By specifying ARITH complier option we can control the maximum number of digits allowed for decimal numbers (packed decimal, zoned decimal and numeric-edited data items and numeric literals). ARITH(EXTEND) - Max. Number of digits 31.

Converting a file from VB to FB.

2012-03-21T14:02:00.001+05:30

DFSORT can be used to do VB to FB conversion, when sorting, copying or merging. The VTOF or CONVERT and OUTREC operands of OUTFIL can be used to change variable-length (e.g. VB) input records to fixed-length (e.g. FB) output records. VTOF or CONVERT indicates that conversion is to be performed and OUTREC defines the reformatted records. All output data sets for which VTOF or CONVERT is used

Recovering Deleted Flat Files

2012-03-21T13:59:00.000+05:30

Flat files can be recovered by following the below mentioned steps. Start 6 HLIST BCDS DSN('filename') Wait for the system notification Type the command HRECOVER 'filename' and wait for system notification Different variations of HRECOVER are given below. HRECOVER 'filename' recovers with same name HRECOVER ‘old filename’ NEW ('new filename') recovers and assigns new name HRECOVER

AUTOTYPE Suggestion

2012-03-21T13:49:00.002+05:30

How wonderful it feels when Internet explorer suggests names for URLs when we start typing the first few letters! Our mainframe also has the ability to do pretty much the same. Using ‘KEYS’ command on the command line, assign a free PF key with the value ‘AUTOTYPE’. We are all set. Now use 3.4 to go to the Data Set list utility and then type the first few qualifier of the required data

Options on DECLARE CURSOR

2012-03-21T11:58:00.006+05:30

∙ Use FOR READ/FETCH ONLY or WITH UR for retrieval only cursors. ∙ Use OPTIMIZE when you know the accurate number of rows that will be fetched ∙ Use ORDER BY only when sequence is important ∙ Use WITH HOLD statement to prevent COMMIT from destroying the cursor position in batch Programs. ∙ Select only those fields that you truly need ∙ Use only DCLGEN variables as predicates While declaring

Common SQL Codes

2012-03-21T11:51:00.000+05:30

Successful Execution SQLCODE 000 SUCCESSFUL EXECUTION Warning SQLCODE +012 THE UNQUALIFIED COLUMN NAME column-name WAS INTERPRETED AS A CORRELATED REFERENCE +098 A DYNAMIC SQL STATEMENT ENDS WITH A SEMICOLON +100 ROW NOT FOUND FOR FETCH, UPDATE OR DELETE, OR THE RESULT OF A QUERY IS AN EMPTY TABLE +110 SQL UPDATE TO A DATA

Useful List of SYSIBM tables

2012-03-21T11:35:00.000+05:30

SYSCHECKDEP Column references for CHECK constraintsSYSCHECKS CHECK constraint specificationsSYSCHECKS2 (V7) Information about CHECK constraints on DB2 Catalog tables created for V7 or laterSYSCOLAUTH The UPDATE privileges held by DB2 users on table or view columnsSYSCOLDIST Cardinality, frequent value, and non-padded frequent value distribution statistics for the first key column of an index

GDG - A Basic Introduction

2012-02-09T12:32:00.000+05:30

Introduction GDG stands for Generation Data Group. Here a group of files are related functionally or chronologically and can be accessed individually or as a group. These files share a unique name. Every dataset in a GDG has a Generation number and version number. Eg.TESTGDG.DATA.G0001.V00 Subsequent files are named by incrementing the Generation number(G0001-G9999). The current

Ranking and Numbering for Records in DB2

2012-01-23T17:01:00.002+05:30

DB2 supports ranking and numbering in much the same way that Oracle does.The available functions are: ROW_NUMBER(), which simply numbers the returned rows sequentially RANK(), which ranks the results, but, in the case of a tie, gives the same number to each and leaves a gap to compensate DENSE_RANK() operates the same as RANK() but doesn't leave any gaps. The difference in these three

Selecting first few rows in DB2

2012-01-23T16:58:00.000+05:30

DB2's method of performing a Top-N query is the FETCH FIRST clause. You can append these variations to a regular SELECT query: FETCH FIRST ROW ONLY FETCH FIRST 1 ROW ONLY FETCH FIRST integer ROWS ONLY Interestingly, you can also use FETCH FIRST 1 ROWS ONLY FETCH FIRST 5 ROW ONLY They aren't as nice grammatically, but they make it easier to generate queries automatically—you don't

INSPECT in COBOL

2012-01-23T15:40:00.001+05:30

The INSPECT verb has two options, TALLYING and REPLACING. You can do one or the other or both. If both are done, the TALLYING IS DONE BEFORE THE replacing. Some versions of the INSPECT require that all the literals be in quotes. This may call for a redefination if the field is numeric. In using the TALLYING format of the INSPECT, you are tallying into a field that is a counter. This field

COBOL Numeric Data Types - COMP

2012-01-23T15:38:00.000+05:30

The following common COBOL data types are discussed below: Binary Computational (comp) Comp-1 Comp-2 Comp-3 Packed Decimal BINARY Specified for binary data items. Such items have a decimal equivalent consisting of the decimal digits 0 through 9, plus a sign. Negative numbers are represented as the two's complement of the positive number with the same absolute value. The amount of

Special Searching

2012-01-23T11:30:00.000+05:30