OTE (Open Transaction Environment)

What is OTE (Open Transaction Environment)?

Task Control Block 

The open transaction environment (OTE) function was added to CICS Transaction Server for OS/390, Version 1 Release 3 and later versions.

In earlier releases of CICS, CICS ran all user transactions under a single z/OS TCB, the CICS quasi-reentrant (QR) TCB. Direct invocation of other services outside the scope of the CICS permitted interfaces could interfere with the use by CICS of the QR TCB. In particular, requests that resulted in the suspension ("blocking") of the QR TCB, which happens when an MVS wait is issued, would cause all CICS tasks to wait. For example, some services provided by DB2, MVS, UNIX® System Services, or TCP/IP, might result in TCB blocking.

Open Transaction Enviornment

The open transaction environment is an environment where CICS application code can use non-CICS services (facilities outside the scope of the CICS API) within the CICS address space, without interference with other transactions. Applications that exploit the open transaction environment run on their own open TCB, rather than on the QR TCB. Unlike the QR TCB, CICS does not perform sub-dispatching on an open TCB. If the application running on an open TCB invokes a non-CICS service that blocks the TCB, the TCB blocking does not affect other CICS tasks.