# General Substation ES and Operating System Requirements

You have to install TIBCO Substation ES on the z/OS environment.

The following lists are the prerequisites for operating Substation ES:

- Verify that the TIBCO Substation ES software is the correct package for your operating system because multiple versions are available. For details, see Obtaining the Software. It is advisable to obtain the latest version for your environment to gain the benefits of the newest features.
- Authorize the the Substation ES load library USERHLQ`.AUTH` to enable the Substation ES initialization programs to run in supervisor state for part of its execution.

  Before a module can run in supervisor state, you must link-edit it as an authorized module into a partitioned data set (PDS), which you must define as being APF-authorized to the operating system. For the modules supplied with TIBCO Substation ES, the link-editing has been done for you. The modules are link-edited with the authorized attribute (using `SETCODE AC(1)`) and installed in the USERHLQ`.AUTH` library.

- To use Substation ES guaranteed messaging with EMS, activate the z/OS Resource Recovery Services (RRS) component and set the appropriate parameters for activation in CICS and IMS.

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