tersedecompress

TerseDecompress is a java program that can be used to decompress files which have been previously compressed on an IBM Mainframe using the TERSE / AMATERSE program (on IBM z/OS or IBM z/VM).

Purpose & benefit

As java programs can virtually run on any platform / operating system with a JVM, this java decompression program can be very useful if you don't have access to an IBM mainframe but need to analyze or process a file which had been compressed on a IBM mainframe using TERSE on IBM z/OS. With this java version of TerseDecompress, you can decompress those tersed IBM Mainframe files on any workstation or laptop etc. that supports Java.

Updates

Version 5.0.1: July 2023 -- September 2025

• Updated pom.xml to have Maven compile using Java 21
• Allow user to specify only <input file> for text files. Resulting <output file> will be <input file>.txt
• Added C++ port
• Added commit id to the version

Version 5: March 2021

• Support for variable length binary records. Variable length records processed in binary mode will be prefixed with a 4 byte field in the same format as the IBM RDW i.e. 2 byte record length field (including RDW length, big-endian) followed by 2 bytes of zeros.

How to run it

For execution, TerseDecompress needs a JVM runtime environment.

Usage:

java -jar tersedecompress.jar [-b] tersed-file output-file

Default mode is text mode, which will attempt EBCDIC -> ASCII conversion.

The -b flag turns on binary mode, no conversion will be attempted.

Recommendation: Use binary mode if possible. EBCDIC->ASCII conversion is not a lossless process, unless the data strictly contains only characters that are common to both code pages used for the translation, and the original data does not contain line ending characters.

How to build it

To build tersedecompress you need the Java JDK and Apache Maven.

In the project directory (the directory containing pom.xml):

mvn clean package

Unit Tests

The project contains unit tests to verify that the decompression is correct.

Due to the size of the test data, it is stored in a separate git repository and referenced via a submodule. The test data is not required to build tersedecompress, unless you want to run the unit tests.

The test data can be found here: https://github.com/openmainframeproject/tersedecompress-testdata

Descriptions of the data are here: https://github.com/openmainframeproject/tersedecompress-testdata/tree/master/tests

Building with Unit Tests

1. Initialize (download) the submodule containing the test data: git submodule update --init
2. Build with unit tests: mvn -DskipTests=false clean package

How to report problems and get support/help

If you have a problem / need help with TerseDecompress.java, please create a GitHub issue.

There is also a Slack channel: https://slack.openmainframeproject.org channel #tersedecompress