Extended Format files (DSNTYPE=EXTREQ or EXTPREF) are not supported as Database or Journal files. Attempts to open such files with IDMS software will result in System abend 213 reason code B8.
Support for DSNTYPE=LARGE database files was added in release 17.0. Still must be a single volume. IDMS does not support multi-volume files
CA IDMS Release Summary r17 SP1
Support for Large and Extended Format Files CA IDMS now supports large format single volume files in z/OS for database and journal files and both large and extended format for work files dynamically created by the REORG utility. Both large and extended format files can have more than 65,535 tracks on a single volume. For more information about large and extended format files, see the IBM documentation. This feature requires z/OS version 1.7 or later.
Large Format Database and Journal Files
The ability to allocate large format database and journal files means that fewer files need to be defined, referenced, and managed leading to a reduction in the administrative effort associated with large database environments.
To use this feature, define a database or journal file whose size in tracks exceeds 65,535. When creating the file, specify DSNTYPE=LARGE in your JCL and be sure to allocate the file on a single volume.