---
title: "Data Integrity in CICS During Updates to VSAM Files"
description: "CICS supports read integrity while reading a file. This feature you can see especially while reading remote files in RLS mode."
url: https://srinimf.com/2016/04/26/how-file-read-in-cics-with-update-option-maintains-integrity/
date: 2016-04-26
modified: 2026-10-10
author: "Srini"
image: https://i0.wp.com/srinimf.com/wp-content/uploads/2016/04/cics-rules.png?fit=509%2C339&ssl=1
categories: ["CICS"]
tags: ["CICS file read", "CICS tips and Tricks"]
type: post
lang: en
---

# Data Integrity in CICS During Updates to VSAM Files

Data integrity is CICS’s internal architecture during updates of VSAM files. UPDATE guarantees read integrity. The mechanism used to ensure data integrity depends on the type of file resource.

Related[CICS Files, What’s CONSISTENT Option](https://srinimf.com/2016/02/23/cics-file-read-command-option-consistent/)

![Data integrity](https://i0.wp.com/srinimf.com/wp-content/uploads/2016/04/pexels-photo-3846021.jpeg?resize=1880%2C1253&ssl=1)*Photo by Anna Shvets on [Pexels.com](https://www.pexels.com/photo/crop-unrecognizable-doctor-with-vision-test-device-3846021/)*

## Data Integrity [in CICS](https://srinimf.com/2016/01/20/5-thoughts-on-cics-ridfld-updating-a-vsam-record/)

Integrity is a mechanism that explains how CICS handles it for various files.

- For a VSAM file accessed in RLS mode, the record to be updated is locked by the SMSVSAM server.
- For a VSAM file accessed in non-RLS mode, the record to be updated is locked by CICS and, in addition, the control interval containing the record is held in exclusive control by VSAM.
- For a VSAM file accessed in non-RLS mode, and log(UNDO), CICS holds a record lock until the task syncpoints.
- For a BDAM file, the record to be updated is held in exclusive control by BDAM.
- For a user-maintained data table, the record to be updated is locked by CICS.
- For a CICS-maintained data table, the record to be updated is locked by CICS and, in addition, the control interval containing the record is held in exclusive control by VSAM. The VSAM control interval lock is required because changes to the data table are reflected in the source data set, which is accessed in non-RLS mode.

Related Posts

- [CICS Files, What’s CONSISTENT Option](https://srinimf.com/2016/02/23/cics-file-read-command-option-consistent/)DateFebruary 23, 2016
- [CICS Record Level Sharing (RLS)](https://srinimf.com/2016/04/20/how-cics-rls-mode-handles-during-files-updates/)DateApril 20, 2016
- [Syntax for DASD Files READ, WRITE, REWRITE and DELETE in CICS](https://srinimf.com/2015/01/17/cics-vsam-files-and-key-points/)DateJanuary 17, 2015

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