If a VSAM TBOPT file is to be used, it has to be defined in CICS. With full support of QSAM TBOPT files since Version 6, tableBASE has to determine how to access the TBOPT dataset. If it is defined under CICS, then CICS I/O is used to read it; if not, and the DD is present, MVS I/O will be used. Note that a CICS TBOPT definition is not sent out.
Starting with Version 6, tableBASE does not initialize if there are apparent user errors in defining TBOPT. If the CICS definition is found, it is assumed that TBOPT is desired, and an error is generated if the VSAM TBOPT file cannot be found.