From Just Solve the File Format Problem
InstallShield Z format is a compressed archive format used by version 3 of the InstallShield installation software. As far as we know, it is a proprietary format that has not been decoded.
Files begin with bytes
13 5D 65 8C 3A 01 02 00.
- Universal Extractor
- InstallShield File Compressor: Official compressor/decompressor utility (Windows command-line). Several different versions of it can be found on the internet (as icomp.zip, icompx.zip, icomp95.zip, ...). Included with Universal Extractor.