A VSAM file that has never contained a record is treated as unavailable. Attempting to open for input will fail. An empty file can be opened for output only. When you open for output, COBOL will write a dummy record to the file & then delete it out.

VSAM distinguishes between an empty data set (that is, one that has never had a record in it) and a data set with no records (for example, adding a record to a KSDS and then deleting it). The difference is that for each write to a VSAM data set, a pointer is updated to reflect the highest used RBA. If you have never written any data to the data set, this pointer has no value and hence causes VSAM problems when attempting to use it to locate the end of the used data. Any program attempting to open a VSAM data set for input before anything has been written to the data set will have a problem & amend will happen with return code 35 as VSAM is unavailable.

Initializing VSAM File Status (Program)

• To initialize the VSAM, you can open it once in output mode and close it in the program during initialization, it could solve your problem. After that again open it in I/o mode.
• Write a step in JCL that delete defines VSAM and REPRO some records from a flat-file Say GDG version this step should be executed before the program uses VSAM.

Initializing VSAM File Status (Manually)

• Open the VSAM file in EDIT mode in File Manager.
• Insert any record in the VSAM file and save.
• Delete that record & save it will initialize the VSAM file.

Example

 //STEP010 EXEC PGM=IDCAMS
 //SYSPRINT DD SYSOUT=*
 //SYSOUT   DD SYSOUT=*
 //SYSIN    DD *
  DELETE  XXXXX.TEST.VSAM        PURGE CLUSTER   
  DEFINE CLUSTER(NAME(XXXXX.TEST.VSAM)          - 
                VOLUME(* *)                     -  
                UNIQUE                          -   
                SHAREOPTIONS(3 3)               - 
                CYLINDERS(7 7))                 - 
              DATA (NAME(XXXXX.TEST.VSAM.DATA)  -    
                KEYS (29 0)                     - 
                RECORDSIZE(35 35)               - 
                CISZ(4096))                     -   
             INDEX (NAME(XXXXX.TEST.VSAM.INDEX) - 
                NOIMBED NOREPLICATE)   
 /*
 //STEP020  EXEC PGM=IDCAMS       
 //IN   DD  DSN=XXXXX.TEST.PS,DISP=SHR      
 //OUT  DD  DSN=XXXXX.TEST.VSAM,DISP=SHR   
 //SYSOUT   DD  SYSOUT=*    
 //SYSPRINT DD  SYSOUT=*          
 //SYSIN    DD  *
   REPRO INFILE(INF) OUTFILE(OUTF) COUNT(1)
 /* 

VSAM File Status Resolution

Code	Typical meaning	Common causes	Recommended action
00	Successful completion	Normal I/O	Continue processing
02	Non-unique alternate key condition	AIX non-unique read condition	Validate access path and logic
04	Length mismatch / boundary-related record issue	LRECL mismatch, variable-length inconsistency	Check layout, copybook, and record format
10	End of file / no more records	Sequential browse complete	End loop cleanly
14	RRDS relative record out of range	Invalid RRN or slot	Validate record number and file size
20	Invalid key / sequence issue	Bad key value, wrong sequence	Check key definition and access mode
21	Duplicate or sequence error	Insert to existing key, bad REWRITE key change	Handle as business duplicate or fix key logic
22	Duplicate primary key	KSDS duplicate insert	Route to duplicate handling process
23	Record not found / permanent read issue	Search miss, incorrect key, deleted data	Recheck key, indexing, and data load integrity
24	Key outside boundary	High/low key violation	Validate key range and start position
28	Space issue	CI/CA exhaustion, file full	Reorganize or extend cluster
30	Permanent I/O error	Device, dataset, or media issues	Escalate to storage/operations; inspect logs
34	Boundary violation	Relative or sequential boundary issue	Verify access mode and record position
35	Open failure / file not present / definition issue	Missing DD, wrong DISP, missing catalog entry	Check JCL and file definition
37	Wrong open mode	INPUT vs I-O vs OUTPUT mismatch	Correct COBOL OPEN mode
38	File locked	Share or enqueue conflict	Review sharing, batch overlap, and CICS serialization
39	Conflicting file attributes	DD/COPYBOOK mismatch, wrong organization	Align program and data set definition
41	File already open	Logic error	Prevent double open in run unit
42	Close on non-open file	Logic error	Guard CLOSE with state checks
43	REWRITE without prior READ for update	Program sequence error	Ensure successful READ before REWRITE
44	Length mismatch on REWRITE	Record length changed unexpectedly	Preserve original record format
46	Read beyond EOF / no current record	Bad sequential flow	Check 10 and EOF condition logic
47	READ on file not open for input/I-O	Wrong mode or control flow	Open correctly before READ
48	WRITE on file not open for output/I-O	Wrong mode	Correct OPEN mode
49	DELETE/REWRITE on file not open I-O	Wrong mode	Ensure I-O access before update verbs
90	Unsuccessful I/O operation	Generic failure	Use VSAM detail and job logs
91	Authorization failure	Security / access control	Verify authority
92	Logic error	Program sequencing	Add state validation and unit tests
93	Resources unavailable	Buffer, latch, or sharing issue	Review resource contention and environment
94	Sequential record unavailable / concurrent open error	Sharing conflict	Check serialization and access rules
95	Invalid or incomplete file info	Bad attributes or missing definitions	Verify DD and file definition
96	No DD statement	JCL allocation missing	Add or fix DD statement
97	Open successful and integrity verified	Successful open with verification	Continue processing
98	File locked	Dataset lock / allocation issue	Clear contention or wait/retry
99	Record locked	Locked record access failed	Retry under proper lock strategy

VSAM return code 00        – SUCCESSFUL COMPLETION

Root Cause:

• The Length of the record does not match the properties or attributes defined for the length of the file. 
• The file is a Variable Length block file but you defined a fixed-length block in your FD clause. Most of the time, this error occurs while reading from a  file or writing to a file.

Fix:

• Assign the proper record length of your  file in the DCB Parameter and match it with the length provided in the FD clause of your COBOL Program.

VSAM return code 04 – READ, WRONG LENGTH RECORD 

Root Cause: The logical error in the program

Fix: The Logic of the COBOL Program itself is wrong so you need to correct the logic of the program.

VSAM return code 13 – File Not Found

Root Cause: File Not Found

Fix: Provide the correct details of the file name. Check if the path of your VSAM file is correct.

VSAM return code 16 – Accessing VSAM file Error

Root Cause: It depends on the type of file, the program used to access the VSAM file and is mostly related to accessing 

Fix: Fix will be based on the way you are accessing the file from a program. Are you trying to update a  file for which you do not have permission?

VSAM return code 19 – Accessing VSAM file Error

Root Cause: In case you are accessing the VSAM file in CICS and you did not provide a proper entry of the  file

Fix: Check if the PCT entry of the file is proper.

VSAM return code 20 – INVALID KEY VSAM KSDS OR RRDS

Root Cause: In the case of  KSDS or RRDS, the key is an INVALID KEY

Fix: Correct the KEY. Check the position, definition, etc and correct it.

VSAM return code 22 – DUPLICATE KEY

Root Cause: Duplicate key defined for  Indexed or relative Files. Duplicate alternate key but the alternate key is defined as unique.

Fix: Remove the duplicate entry of the key.

VSAM return code 23 – RECORD NOT FOUND or FILE NOT FOUND

Root Cause: The record is not found when you are trying to access using a key. File not found.

Fix: Check if the record is correct or the path to access the file is given correctly.

VSAM return code 24 – Invalid Key – key outside the boundary of file.

Root Cause: Trying to write beyond the boundary in case of Relative and indexed files using the key. The size of the Relative Record number is larger.

Fix: Do not write beyond the boundary or change the boundary.

VSAM return code 28 – Unable to extend the dataset

Root Cause:

• The primary space is already exhausted and the space in Secondary space cannot be extended further due to the limitation in space.
• The Index CI is not large enough

Fix: Check with your storage group or try to give less value to your secondary allocation.

VSAM return code 35 – OPEN, FILE NOT PRESENT

Root Cause: You are trying to open a file that is not present.

Fix:

• Check why the file is not present? Are you providing the correct filename with the correct path?
• Initialize the file using any of the above method.

VSAM return code 37 – Open file error due to opening mode

Root Cause: You are trying to open a  file in a particular mode that is not allowed for that file.

Fix: Check the file opening modes available for the file and fix it.

VSAM return code 39 – LOGIC ERROR 

Root Cause:

• The Unsuccessful opening of a  file due to the conflicting attributes of the file.
• Wrong value in DCB which is not matching the file attributes in the Program.

Fix: Check the file attribute in the actual file, the file attributes defined in the FD section of the program,  the record length in your DCB Parameter and the record mode, etc.

VSAM return code 41 – OPENING A FILE THAT IS ALREADY OPENED 

Root Cause: You are trying to open a  file in a particular mode that is not allowed for that file.

Fix: Check the file opening modes available for the file and fix it.

VSAM return code 42 – CLOSING A FILE WITHOUT OPEN. 

Root Cause: When the file is already closed and you try to do a CLOSE operation once again on the file which is already closed.

Fix: Change the program to make sure that you do not give a CLOSE file on the file which is already closed.

VSAM return code 46 – SEQUENTIAL READ WITHOUT POSITIONING

Root Cause: If you try to sequentially read a  file even when the end of the record is reached.

Fix: Once the End of the File is reached, do not read the file.

VSAM return code 47 – READING FILE NOT OPEN AS INPUT/IO/EXTEND

Root Cause: File not opened in INPUT or I-O mode.

Fix: Open the file in INPUT or I-O mode.

VSAM return code 90 – Unsuccessful OPEN, READ, WRITE or CLOSE operation

Root Cause:

• Unsuccessful OPEN, READ, WRITE or CLOSE operation.
• You defined ‘LINE SEQUENTIAL’ for  file
• You missed to initialize the  file before OPEN, READ or WRITE statement.
• If you are trying to open an empty file or a file which does not exist and you have not tried to capture the return code of the OPEN or READ or WRITE, then you can get this generic error.
• There can be other reason for status code 90 as well as this error is not a specific rather a generic error.

Fix:

• If you have coded ‘LINE SEQUENTIAL’ then remove it.
• Code the file status for OPEN, READ, WRITE or CLOSE operation and see where you are getting the error so that you can easily fix that.

VSAM return code 91 – Password or authorization failed

Root Cause: Password Failure. Authorization failure.

Fix: Check the password which is given for VSAM file or whether you are authorized to access the file or not?

 

VSAM return code 92 – LOGIC ERROR / OPENING A OPEN FILE  / READING OUTPUT FILE  / WRITING INTO A INPUT FILE  / DEL or REW BUT NO PRIOR READ

Root Cause:

• Logic error.
• Common logic errors are like a wrong way of Opening the file, improper way of reading the  file or Writing the  file.

Fix:

• Check the logic of the program mentioned above and fix it.
• The most common status code 92 is ‘VSAM file status 92 while writing’ and you need to fix the logical error related to write or rewrite. Check if the file is opened correctly for writing

VSAM return code 93 – OPENING A FILE THAT IS ALREADY OPENED 

Root Cause:

• Resource not available.
• Storage is insufficient for 
• Extents used up and extra extents not available

Fix: Check with your storage group.

VSAM return code 96 – MISSING DD STATEMENT IN JCL 

Root Cause: Missing DD statement for the VSAM or QSAM file.

Fix: Code the missing DD statement in the JCL

VSAM return code 97 – OPEN OK, FILE INTEGRITY VERIFIED

Root Cause: OPEN file successful and the file integrity verified. This might happen when a previous Job did not close the  file so VSAM has to verify the integrity of the file.

Fix: Check the file opening modes available for the file and fix it.

VSAM return code 100 – Improper loading  

Root Cause:

• Improper loading of  file.
• Loading of a cluster using REPRO failed.

Fix: Before building the alternate index(AIX) and path, you need to load the cluster.

VSAM return code 160 – input file might be empty

Root Cause: The input file might be empty when you try to open it.

Fix: Check with your storage group.

VSAM return code 168 –  The device type is not supported

Root Cause: The device type is not supported.

Fix: Check with your admin.

 

Symptom	Likely cause	First check	Next step
OPEN returns 35	Missing DD, wrong DISP, catalog issue	JCL and LISTCAT	Fix allocation or catalog entry
READ returns 10	EOF reached	Sequential loop logic	Exit loop cleanly
WRITE returns 22	Duplicate key	Business rule or source data	Quarantine duplicate and continue or reject
REWRITE returns 43	No prior READ for update	Program flow	Ensure positioned record exists
DELETE returns 49	Not opened I-O	OPEN mode	Switch to I-O
90/93/95 class code	Environmental or resource issue	VSAM detail + job log	Resolve security, resource, or definition issue

 

Decision tree

Use this decision path for rapid triage:

1. Did the failure occur at OPEN? If yes, inspect JCL, DD allocation, catalog entry, and data set attributes.

2. Did it occur on READ/WRITE/REWRITE/DELETE? If yes, confirm OPEN mode, file organization, and verb sequencing.

3. Is the status in the 20s? If yes, inspect key logic, duplicate handling, and file positioning.

4. Is the status in the 30s or 90s? If yes, inspect the environment, security, locks, resources, and definition integrity.

5. Is the file interrupted after an abend? If yes, run VERIFY ... RECOVER and then EXAMINE.

Case studies

Case 1: Duplicate insert in KSDS. A nightly load received status 22 because the upstream system resent a customer number already present in the cluster. The team changed the load to separate new inserts from correction updates and routed duplicates to a reject file.

Case 2: Open failure after deployment. A new COBOL package returned status 35 because the DD statement was missing in the promoted JCL stream. The fix was to align the deployment checklist with catalog validation and automated LISTCAT verification.

Case 3: Interrupted update after abend. A KSDS was left in an uncertain state after a CANCEL. Operations ran VERIFY DATASET(... ) RECOVER, then EXAMINE to confirm health before resuming REPRO processing.

Top 10 mistakes

1. Not checking FILE STATUS after every verb.

2. Using the wrong OPEN mode for the intended operation.

3. Ignoring duplicate-key handling in KSDS loads.

4. Assuming 35 is always a data problem instead of a JCL or catalog issue.

5. Rewriting without confirming prior READ for update.

6. Missing or stale PATH/AIX definitions after base-cluster changes.

7. Reloading data without structural validation.

8. Overbuffering without measuring paging impact.

9. Mixing batch and CICS assumptions about locking and sharing.

10. Treating VSAM Initialization as a one-time task instead of a lifecycle process.

Interview questions

Q1. What is the difference between COBOL file status and VSAM status?
COBOL file status is the high-level two-byte result code, while the VSAM status area provides more detailed return information for VSAM files.

Q2. When should you use EXAMINE and VERIFY?
Use them after interrupted VSAM processing or when structural integrity is in doubt; VERIFY ... RECOVER followed by EXAMINE is a common recovery pattern.

Q3. What is the main difference among KSDS, ESDS, and RRDS?
KSDS is key-based, ESDS is creation-order/RBA-based, and RRDS is relative-record-number based.

Q4. Why is status 35 so common in production?
Because it often signals environment or definition issues such as missing DDs, wrong dataset attributes, or catalog problems.

Q5. How do you handle duplicate keys in a KSDS load?
Treat them as expected business exceptions where appropriate, or reject them with an audit trail and a remediation path.

Q6. During the processing of a VSAM file, some system error occurs and it is subsequently unusable how to fix this issue?

Run VERIFY

Q7. How do you fix the problem associated with VSAM file status out of space condition?

• Define new VSAM dataset allocated with more space.
• Use IDCAMS to REPRO the old VSAM file to the new VSAM dataset.
• Use IDCAMS to ALTER/rename the old VSAM dataset or use IDCAMS to DELETE the old VSAM dataset.
• Use IDCAMS to ALTER/rename the new VSAM dataset to the name of the original VSAM dataset.

Q8. What are VSAM file status codes?

They are COBOL status values that report the result of VSAM file operations such as OPEN, READ, WRITE, REWRITE, DELETE, and CLOSE.

Q9. What is VSAM initialization?
It is the process of defining, deleting, verifying, and loading a VSAM cluster so it is structurally ready for application use.

Q10. How do you initialize a VSAM file in IDCAMS?
A common pattern is DELETE, DEFINE CLUSTER, and then REPRO to load data.

Q11. What does COBOL status 35 mean for VSAM?
It usually indicates an open failure or related definition problem, often involving JCL, catalog, or file attributes.

Q12. Why use a second FILE STATUS item for VSAM?
Because it provides more detailed return information than the two-byte COBOL status alone.

Q13. What is the best first step in VSAM troubleshooting?
Check the verb, the status code, the OPEN mode, and the DD/catalog definition.

 

Conclusion

VSAM mastery comes from combining correct definitions, disciplined COBOL error handling, and repeatable initialization and recovery procedures. If you standardize FILE STATUS checks, automate IDCAMS validation, and document your recovery paths, you will reduce outages and shorten triage time.
For deeper learning, explore related mainframe topics such as COBOL file handling, IDCAMS utility patterns, JCL utilities, CICS file control, and DB2 integration to build a complete enterprise data-processing toolkit.

 

VSAM Interview Questions : Click Here. IBM Reference : Click Here