# Prerequisites

## RED Initialization Parameters for CICS

You must set the following CICS System Initialization Parameters for Substation ES to connect to a CICS Region:

    PLTPI=RI
    PLTSD=RD

Review `USERHLQ.ASM(SXXACFGC)`, which contains the parameters that can be used to configure the RED interface. You might not have to make changes to it.
Note: RED transactions (#RED) use CICS OTE. Review your MAXOPENTCB parameter to ensure it is greater than the transaction interface for RED parameter CICS-MAIN-MAX which defaults to 21.
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