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IMS Technology Update Knowledge Base Computer Education CETi

IMS Transaction and Database Server

IBM has made changes to IMS which improve uptime, scalability, system management of network communications, managing input/output processing, and security. The expanded IMS featureset includes message queuing, logging and recovery, and checkpoint/restart that run in a data sharing environment - batch messages and programs.

According to IBM, its client's have been increasing IMS usage; the recent highest growth has been at small installations. The acceleration in IMS projects typically is part of a modernization and server consolidation strategy. Operational cost savings have been driving utilization of IMS; MIPS are 50% lower than relational technology and storage is 25% less expensive. This translates into high volume at a low cost per transaction. IMS provides built-in recovery, failover architecture, and supports a Sysplex environment; an IMS transaction server is not a single point-of-failure.

The IMS interfaces and application development front ends that can be used with installation, application development, and reporting:

IMS Tools Java EE SQL/JDBC pureQuery
Rational Optim Cognos InfoSphere

There is an expanded integration of IMS application program development and maintenance with Rational Developer for System z and IMS Tools.

IMS Version 13

IMS 13 provides native SQL support for COBOL. This allows applications to directly access and process IMS databases. Database versioning offers flexibility for implementing database changes and expediting new program deployment without the requirement to roll out changes to existing programs. There is TCP/IP support for ISC: Intersystem Communication links between IMS and CICS; this can be used to reduce the costs associated with maintenance.   There is additional support for Java.

IMS Version 12

Batch Data Sharing
Batch data sharing jobs survive CF cache structure access failures. OSAM and VSAM structures can be moved and rebuilt while batch jobs are executing.


Fast Path: 64-bit buffer pool

There is a more efficient use of subpools and reduced ECSA usage. Fast Path pool is more dynamic. Additional buffers are moved from ECSA to 64-bit storage. Enhancements have been made to the Query POOL command.

Fast Path DEDB secondary indexing

Secondary indexes for a DEDB: Data Entry Database are maintained by IMS; IMS does not build secondary indexes. Access to DEDB is implemented through an alternative key. Sequential processing is performed using an alternative key or alternative segment type.

Fast Path logging

There are options for reduced logging in replication and disaster recovery. Instead of only changed data, entire segments for REPL calls can be logged. For VSAM, the VSAM pools can be used for tuning database performance.

VSAM database buffer pools have been increased from 16 to 255. Up to 255 POOLID statements can be specified in a DFSVSMxx member or DFSVSAMP dataset. Additional VSAM subpools can be implemented. 

CICS Transaction Server
Threadsafe access between CICS and IMS allows EXEC DLI and CALL DLI calls from CICS to be made without any TCB switching overhead. This translates into CPU savings and increased throughput for IMS DBCTL clients. Batch Data Sharing Batch data sharing jobs survive CF cache structure access failures.

DBRC: Database Recovery

CETi technology partners provide guidance on how to:

  • Streamline the RECON through deletion of Change Accum execution information.
  • Use the expanded number of keys, from 32 to 64, in skeletal JCL.
  • Apply the LIST command enhancements - RMLIST, LIST.DS, and LIST.DBDS.
    • Output for /RMLIST command entered through OM API can exceed 32K.
    • There is a new NORCVINF keyword for LIST.DB and LIST.DBDS for eliminating unneeded output.


  • Add user data to the IC, RECOV, REORG, and CA RECON records.
  • Manage the CA retention period through the CA Group record for recording CA executions.
  • Use LIST.HISTORY output for generating additional dataset information.
  • Use the expanded capacity of LIST.RECON; there can be up to 32,767 registered databases.
  • Use the Database Recovery utility and the value in RECON for setting and managing the partition reorganization number.

IMS Version 10 and 11

IMS System Software Enhancement
System Operations Manager, Sysplex resource management, and IMS Connect
Transaction Manager MSC: Multiple Systems Coupling, OTMA: Open Transaction Manager Access and Connectivity, and IMS and Java
Database Manager IMS XML and IMS and Java

Prior to IMS 11, OLR: Online Reorganization issued VSAM GET requests for sequential retrieval from an input dataset. It is a direct access option in the RPL: Request Parameter List. VSAM uses one or more index levels to retrieve the data control interval. OLR is a sequential input dataset process. It uses the VSAM sequential access option to issue KSDS GET requests for sequential retrieval from input datasets. This reduced CPU and elapsed time.

SYS-ED workshops explain and demonstrate:

  • How the IMS database management system organizes the data in different structures to optimize storage and retrieval, and ensure integrity and recovery.
  • The integration and open access with new application development and connectivity.
  • How to broaden user access.
  • Access through web, Java, XML, and Linux.
  • Auto-application-generation tools.
  • How to use autonomic computing.
  • Utilization of end-to-end transaction integrity.
  • Real-time data currency.

Corroborating Source:


IMS Release 12 Share presentation - Richard Lewis.