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Q: How does SEARCH ALL differ from SEARCH?
Answer:
SEARCH performs a sequential/linear search from the current index position. SEARCH ALL performs a binary search requiring the table to be sorted (ASCENDING/DESCENDING KEY clause) and indexed. SEARCH ALL is faster for large tables but requires sorted data.
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Q: Explain STRING and UNSTRING operations
Answer:
STRING concatenates multiple fields into one: STRING field-1 DELIMITED BY SPACE field-2 INTO output-field. UNSTRING splits one field into multiple: UNSTRING input-field DELIMITED BY ',' INTO field-1 field-2. Both support POINTER for position tracking and OVERFLOW handling.
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Q: Explain START statement for VSAM
Answer:
START positions for sequential READ. START filename KEY IS EQUAL/GREATER/NOT LESS THAN key-field. After successful START, READ NEXT retrieves records sequentially from that position. INVALID KEY handles not-found condition.
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Q: What is RRDS in VSAM?
Answer:
RRDS (Relative Record Dataset) accesses by relative record number (slot). Fixed length slots numbered 1, 2, 3... Can be empty slots. Good for direct access by position. Less common than KSDS/ESDS.
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Q: How to use STRING with POINTER?
Answer:
STRING uses POINTER to track position: STRING field-1 DELIMITED SIZE INTO output WITH POINTER pos-var. Pointer shows next available position. Initialize before first STRING. Check for overflow. Continue STRING in multiple statements.
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Q: Explain SYMBOLIC CHARACTERS
Answer:
SPECIAL-NAMES. SYMBOLIC CHARACTERS NULL-CHAR IS 1. Assigns name to ordinal position in collating sequence. Position 1 is X'00' in EBCDIC. Use: MOVE NULL-CHAR TO field. Define non-printable characters readably.
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Q: How to handle variable length KSDS?
Answer:
Define with RECORDSIZE(avg max). Read/write variable length records. COBOL RECORD VARYING clause. Key position fixed. Read returns actual length. Write length implicit from record.
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Q: What is backward READ?
Answer:
READ PREVIOUS for backward sequential. Must establish position first (START or READ). KSDS and ESDS support backward. Useful for end-of-file processing or range searches.
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Q: How to do file BROWSE?
Answer:
BROWSE reads sequentially. EXEC CICS STARTBR FILE(name) RIDFLD(key). READNEXT/READPREV in loop. ENDBR ends browse. TOKEN for concurrent browses. Can use generic key to position.
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Q: Explain DD PATH statement?
Answer:
PATH specifies Unix/USS file. PATH='/u/user/file'. Used instead of DSN. PATHDISP for disposition. PATHOPTS for options. PATHMODE for permissions. Integrates USS files into batch JCL.
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Q: What is PATHDISP parameter?
Answer:
PATHDISP=(normal,abnormal) for USS files. Options: KEEP, DELETE. PATHDISP=(KEEP,DELETE). Used with PATH parameter. Similar to DISP for MVS datasets. Controls USS file retention.
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Q: How to use CURSOR option?
Answer:
CURSOR positions cursor on SEND MAP. EXEC CICS SEND MAP CURSOR(pos). Position number from 0. Or CURSOR option in symbolic map (-1 in length field). Controls data entry flow.
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Q: How to define and use indexes?
Answer:
INDEX defined with OCCURS: 05 WS-TABLE OCCURS 10 INDEXED BY WS-IDX. SET WS-IDX TO 5 sets position. SET WS-IDX UP/DOWN BY 1 changes position. Use SEARCH verb with index. More efficient than subscripts for table access.
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Q: What is reference modification?
Answer:
Reference modification extracts substring: WS-FIELD(start:length). WS-NAME(1:3) gets first 3 characters. Can use in MOVE, IF, DISPLAY. Start position is 1-based. Length optional (to end). More flexible than REDEFINES for variable positions.
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Q: How to read VSAM sequentially?
Answer:
OPEN INPUT file. START if positioning needed. READ NEXT repeatedly until status 10 (end of file). CLOSE file. START optional - defaults to beginning. READ NEXT gets records in key sequence for KSDS.
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Q: How to write VSAM random?
Answer:
ACCESS MODE IS RANDOM or DYNAMIC. WRITE record writes at key position. For KSDS, key must not exist (status 22). For ESDS, writes at end. RANDOM/DYNAMIC MODE required.
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Q: What is CURSOR IS clause?
Answer:
In Screen Section, CURSOR IS field-name positions cursor. ACCEPT screen-name WITH CURSOR. Runtime positions to specified field. Can set dynamically. Used in interactive COBOL (CICS typically handles cursor differently).
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Q: How does DISP parameter work?
Answer:
DISP=(status,normal-end,abnormal-end). Status: NEW/OLD/SHR/MOD. Normal-end: DELETE/KEEP/PASS/CATLG/UNCATLG. Abnormal-end: same options. Example: DISP=(NEW,CATLG,DELETE) creates new, catalogs if OK, deletes if abend. MOD appends or creates if not exists.
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Q: How to SEND MAP to terminal?
Answer:
EXEC CICS SEND MAP(mapname) MAPSET(mapsetname) FROM(symbolic-map) ERASE. CURSOR option positions cursor. FREEKB unlocks keyboard. ALARM sounds alarm. MAPONLY sends without data. DATAONLY sends only modified fields.
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Q: Explain JES2 control cards
Answer:
JES2 cards start with /*. /*JOBPARM limits resources. /*ROUTE sends output. /*OUTPUT JESDS specifies JES output. /*PRIORITY sets priority. Process by JES2, not passed to job. Position after JOB card before first EXEC.
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Q: Explain RRN in CICS
Answer:
RRN (Relative Record Number) for RRDS files. RIDFLD contains RRN, not key. Numeric 1-based slot number. RRN option on file commands. Access by position not content.
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Q: How to override PROC DD?
Answer:
//procstep.ddname DD overrides. //MYSTEP.SYSOUT DD SYSOUT=H changes SYSOUT class. Can add parameters or replace entirely. Add new DD: //MYSTEP.NEWDD DD DSN=... Position after EXEC procname.
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Q: Explain DECLARE CURSOR syntax
Answer:
DECLARE cursor-name CURSOR FOR SELECT... WITH HOLD keeps open after COMMIT. WITH RETURN returns to caller. FOR UPDATE OF allows positioned update. FOR READ ONLY optimizes read. ORDER BY for sorting. Static or dynamic declaration.
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Q: What is SUBSTR function?
Answer:
SUBSTR extracts substring. SUBSTR(string, start, length). SUBSTR(name, 1, 3) gets first 3 chars. Position starts at 1. Length optional (to end). Can use in WHERE for pattern matching.
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Q: Explain ORDER BY options
Answer:
ORDER BY sorts results. ORDER BY col1 ASC, col2 DESC. ASC default. NULLS FIRST/LAST controls NULL position. Ordinal: ORDER BY 1, 2 uses column positions. ORDER BY CASE for custom order. Affects performance.