IMS COMPRESSION -- Extended Release 2 Improves Data Compression Performance for IMS Databases

Software Announcement
August 29, 1995
Announcement Letter Number: 295-374

Table of Contents:

In Brief . . .

IMS COMPRESSION-Extended Release 2 now provides:

  • New one pass analysis and reporting function reports
    • detail by segment type
    • custom and generic dictionary performance
    • segment size distributions for planning
  • Revised and expanded documentation
    • Compression concepts explained
    • Implementation strategies discussed
  • Function to bypass prefix and key data
  • Option to specify compression start byte
  • Segment selection for HD Unload files
  • Improved easier-to-use ISPF frontend
  • Revised and expanded reporting

IMS (TM) COMPRESSION -- Extended Release 2 assists database administrators and system programmers to build, implement, and evaluate data compression routines for use in the IMS/ESA (R) database environment. The Ziv-Lempel technology used provides excellent data compression and, when coupled with the appropriate hardware, CPU overhead is minimized.

The new release of this easy-to-use tool provides new and revised features that help reduce the time needed to analyze databases for potential compression implementation. Now, with one pass, all segments of a database can be analyzed. Additionally, new and revised reports provide more information, including segment size distributions, that help you select segments to compress and plan optimal compression strategies for any IMS database. The expanded Users Guide now contains discussions on compression concepts and strategies to further aid implementation planning.

Planned Availability Date: September 15, 1995

 (TM) Trademark of International Business Machines Corporation
 (R)  Registered trademark of International Business Machines


This announcement is provided for your information only. For additional information, contact your IBM representative, call 800-IBM-4YOU, or visit the IBM home page at: %+%Start_URL%+%


IMS COMPRESSION -- Extended provides database administrators and systems programmers with easy-to-use tools for analyzing and implementing hardware assisted data compression for IMS/ESA databases. A generic dictionary is included with the product. The generic dictionary provides varying degrees of compression depending on database content. With minimum effort, good compression can be obtained using the generic dictionary. However, when maximum compression is required, IMS COMPRESSION -- Extended provides the following features and functions to help make analysis and implementation quick and easy.

Analyze Function

This function models compression dictionaries based on input provided and predicts potential compression savings. This function is expanded in Release 2 and now, in one pass, predicts compression savings by segment type for a database. In addition, results for both Custom and Generic dictionary implementations are predicted and reported. Segment Key data can now be excluded from the analysis and build operations and a new report is added to show segment size distributions to help in the selection of and planning for segment compression.

The following data sources are supported and with Release 2, segment types can be selected from HD Unload datasets as well as Imagecopy datasets.

  • IMS Unload

  • IMS Imagecopy

  • Data Base Tools (DBT) HSSR unload

  • Data Base Tools (DBT) DEDB unload

  • User extracted segment data

Build Function

The Build function creates compression dictionaries and the segment edit/compression routine for implementation. JCL is provided to regenerate the DBD and the dictionary and statistics are retained for later use by the examine function.

Examine Function

This function is used to evaluate the effectiveness of compression routines in service. As databases change over time, so can the effectiveness of the compression algorithm. This feature allows the user to evaluate the situation periodically and take action as needed.

Compress Function

The Compress Function assists in implementing compression. JCL is provided supporting IMS reload utilities.

Optimal Performance

IBM provides additional products useful in implementing data compression for IMS/ESA database. These performance products help reduce the time needed to implement compression for IMS. These products are all separately orderable features of the IMS DataBase Tools product (5685-093):

  • High Speed Sequential Retrieval (HSSR)
  • Fast Reorganization Reload (FRR)
  • DEDB Unload/Reload
  • Fast ACBGEN


Specified Operating Environment

Hardware Requirements: IMS COMPRESSION -- Extended is most effective when used with IBM ES/9000 (TM) processors with the hardware assisted data compression feature. If the hardware instruction is not installed on the processor, MVS/ESA (TM) SP (TM) 4.3 supports the compression by simulating the hardware instruction.

One nine-track tape drive or IBM 3480 tape unit is required for installation and maintenance.

Software Requirements: IMS COMPRESSION -- Extended requires MVS/ESA SP 4.3 or later and supports the following IMS/ESA Database Manager Versions:

  • IMS/ESA Version 5 for IMS/ESA Database Manager (5695-176)
  • IMS/ESA Database Manager Version 4 (5685-012)
  • IMS/ESA Database Manager Version 3 (5665-408)
DEDB fastpath database compression is not supported in the IMS/ESA Version 3 environment. DEDB fastpath database compression is supported in IMS/ESA Version 4.1 or later.

Compatibility: IMS COMPRESSION -- Extended Version 1.2 is upward compatible with IMS COMPRESSION -- Extended Version 1.1.

User Group Requirements: This announcement satisfies or partially satisfies four requirements from one or more of the worldwide user group communities, which include Australasian SHARE/GUIDE (ASG), COMMON, COMMON Europe, GUIDE International, G.U.I.D.E. Europe, Japan GUIDE/SHARE (JGS), Guide Latin American (LAG), SHARE EUROPE and SHARE Incorporated.

  • R00045642 -- Create dictionaries for multiple segments in one pass

  • R00046025 -- Ability to indicate prefix/key length for dictionary build

  • R00046026 -- Create individual dictionaries for each segments from DB unload

  • R00045639 -- Pad bytes for compressed variable length segments

Planning Information

Security, Auditability, and Control

The announced program uses the security and auditability features of the supported IMS and/or MVS systems.

User management is responsible for evaluation, selection, and implementation of security features, administrative procedures, and appropriate controls in application systems, and communication facilities.


The following advance publications are available now. To order, contact your IBM representative.

Title                        Number          Availability Date

IMS COMPRESSION -- Extended Users Guide SC26-8076 September 15, 1995

IMS COMPRESSION -- Extended Licensed Program Specification GC26-8088 September 15, 1995

Current Licensees

Current licensees of IMS COMPRESSION -- Extended Version 1 Release 1 will be sent a program reorder form which may be returned directly to IBM Software Manufacturing Solutions (SMS). The mailing of these reorder forms is scheduled to be completed by September 29, 1995. Reorder forms returned to SMS will be processed within 10 work days of receipt. When new release is available, prior release will no longer be available.

New Licensees

Orders for new licenses will be accepted now.

Shipment will begin on the planned availability date.

Orders that ship prior to the planned availability will receive IMS COMPRESSION -- Extended Release 1.

Orders that ship after the planned availability date will receive IMS COMPRESSION -- Extended Release 2.

New users of IMS COMPRESSION -- Extended should specify:

         Type           Model

5655 085

Basic License: To order a basic license, specify the program number and feature number 9001 for asset registration. Specify feature number 3647 for a monthly license charge or feature number 3648 for a one-time charge. When new release is available, prior release will no longer be available. Specify the feature number of the desired distribution medium shown below.

Basic Machine-Readable Material: To order, select the feature number of the desired distribution medium:

Environment              Number        Distribution Medium

IMS COMPRESSION -- Extended 5801 6250 magnetic tape IMS COMPRESSION -- Extended 5802 3480 tape cartridge IMS COMPRESSION -- Extended 5700 4-mm tape cartridge

Customization Options: Select the appropriate feature numbers to customize your order to specify the delivery options desired. These features can be specified on the initial or MES orders.

Example: If publications are not desired for the initial order, and for future updates, specify feature numbers 3470 to ship media only, and 3480 to ship media updates only. In the future if publication updates were required, order an MES to remove feature number 3480, and the publications will ship with the next release for the program.

Description                                         Number

Initial Shipments

Serial Number Only (suppresses shipment of media and documentation) 3444

Ship Media Only (suppresses initial shipment of documentation) 3470

Ship Documentation Only (suppresses initial shipment of media) 3471

Update Shipments

Ship Media Updates Only (suppresses update shipment of documentation) 3480

Ship Documentation Only (suppresses update shipment of media) 3481

Suppress Updates (suppresses update shipment of media and documentation) 3482

Expedite Shipments

Local IBM Office Expedite (for IBM use only) 3445

Customer Expedite Process Charge ($30 charge for each product) 3446

Expedite shipments will be processed to receive 72 hour delivery from the time SMS receives the order. SMS will then ship the order via overnight air transportation.

DSLO License: To order a DSLO license, specify the program number and feature number 9511 for a monthly license charge or feature number 9512 for a one-time charge.

Ordering a DSLO feature will result in IBM maintaining a record of this customer location as a DSLO user only. All material for the DSLO license must be ordered by the basic licensee. If a user selects DSLO, no other feature numbers are valid for this order and no program materials or updates will be shipped.

Unlicensed Documentation: A memo, program directory and one copy of the following publications are supplied automatically with the basic machine-readable material:

Title                                             Number

IMS COMPRESSION -- Extended Users Guide SC26-8076 IMS COMPRESSION -- Extended LPS GC26-8088

Additional copies of unlicensed publications are available for a fee after product availability. These copies may be ordered from your IBM representative, through the System Library Subscription Service (SLSS) or by direct order.

Displayable Softcopy Publications

IMS COMPRESSION -- Extended manuals are offered in displayable softcopy form. All unlicensed manuals are included. The displayable manuals are shipped on the Transaction Processing and Data CD-ROM (SK2T-0730).

These displayable manuals can be used with the BookManager (R) READ licensed programs in any of the supported environments. Terms and conditions for use of the machine-readable files are shipped with the files.

Subsequent updates (technical newsletters or revisions between releases) to the publications shipped with the product will be distributed to the user of record for as long as a license for this software remains in effect. A separate publication order or subscription is not needed.


The terms for IMS COMPRESSION -- Extended Release 2, as previously announced (Software Announcement 294-369, dated June 7, 1994), licensed under the IBM Customer Agreement are unaffected by this announcement.

Program Currency: Program services previously announced for IMS COMPRESSION -- Extended Release 1, will be available until March 31, 1996.


Contact your IBM representative for charges information for this announcement.

For additional product information, refer to Software Announcement 294-369, dated June 7,1994.

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