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Improved IMS Performance

Service Channel updates provide improvements for IMS 10 and 11

Recent updates to the IBM Information Management System (IMS), the premiere transaction and hierarchical database-management system, provide new functionality, improved performance, and reduced CPU and storage usage for the IMS version 10 and 11 systems currently running in enterprise shops. These enhancements, delivered through the IBM Service Channel, provide the following benefits:

  • Faster conversion of databases to partitioned, high-availability large databases (HALDB)
  • Improved Java performance in IMS-dependent regions
  • Simplified type-2 Java Database Connectivity (JDBC) access to IMS databases
  • Multisegment message support for IMS simple object access protocol (SOAP) Gateway applications
  • Shortened application wait time for call-out requests
  • Avoidance of excessive IMS CPU cycles for users of IMS Transaction Manager (TM) resource adapter
  • Lowered storage usage and improved serviceability for users of Open Transaction Manager Access (OTMA)

This article summarizes the improvements. Enhancement numbers for each feature are available in Table 1.

Parallel Unload for conversion to HALDB

Since IMS Version 7, HALDB has enabled users to partition IMS Hierarchical Direct-Access Method (HDAM), Hierarchical Indexed Direct-Access Method (HIDAM), and secondary index full-function databases to increase their capacity and improve the availability of the data they contain. However, if the full-function database being converted to HALDB was large, the time required for the conversion process—which entails unloading the data from the existing database and then reloading it into one or more partitions of a HALDB database—could be lengthy.

To improve the performance of the conversion process, you can use the IMS HD Reorganization Unload utility (DFSURGU0) to unload ranges of records from the existing database in multiple parallel jobs. Use the values of the record keys to define the ranges to the DFSURGU0 utility.

Persistent JVM Support

To call a Java application from another IMS application programming language in certain types of IMS dependent regions a Java Virtual Machine (JVM) must be instantiated to support the Java application in the dependent region.

Prior to recent enhancements, a new JVM was instantiated each time a Java application was called and then destroyed after the Java application terminated. The frequent instantiation and destruction of the JVMs in the dependent region degraded performance. Now, you can significantly improve performance when Java applications are called from other IMS programming languages by configuring IMS to maintain a persistent JVM for the life of the dependent region, so that the JVM is not destroyed as soon as a Java application terminates. The following types of IMS dependent region support persistent JVMs:

  • Batch message processing program (BMP)
  • IMS Fast Path (IFP)
  • Message processing program (MPP)

Type-2 JDBC Connectivity

IMS universal driver type-2 Java Database Connectivity (JDBC) provides simplified, local database access in z/OS. The IMS universal drivers are software components that provide Java applications with connectivity and access to IMS databases from z/OS and distributed environments through TCP/IP. The universal drivers are built on open-standard technologies that help speed application development.

Previously, the IMS universal drivers provided only type-4 JDBC, which requires both the IMS Connect TCP/IP server and the Open Database Manager (ODBM) components of IMS to access IMS databases. Now, the IMS universal drivers also provide access to IMS databases from IMS dependent regions by using type-2 JDBC connectivity. When using type-2 connectivity, the IMS universal drivers run on the same logical partition as IMS and access IMS databases directly through the Java Native Interface (JNI) and the IMS CEETDLI interface.

Multisegment Messages

The IBM IMS Enterprise Suite SOAP Gateway is a web service solution that allows different types of client applications, such as Microsoft .NET, Java, and other third-party applications, to submit SOAP requests to IMS that drive the business logic of IMS application programs. Multisegment message support for IMS SOAP Gateway applications now allows larger messages.

Prior to this enhancement, IMS didn’t support sending and receiving of multisegment messages between IMS application programs and SOAP Gateway clients. Now, using XML converters that Rational Developer for System z Version 7.5 generates, IMS supports multisegment messages between SOAP clients and IMS application programs that function as Web-service providers.

Ben Johnson is an IBM information developer. He has been writing about IMS since 2003, focusing on both IMS database administration and IMS communications and connections, with a particular interest in OTMA and IMS Connect. He can be contacted at

Jack Yuan is a senior software engineer for IMS development. He can be contacted at



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