The assembler user exit CEEBXITA tailors the characteristics of the enclave before it is established. CEEBXITA must be written in assembler language because an HLL environment may not yet be established when the exit is invoked. CEEBXITA is driven for enclave initialization and enclave termination regardless of whether the enclave is the first enclave in the process or a nested enclave. CEEBXITA can differentiate easily between first and nested enclaves. For more information about nested enclaves, see z/OS Language Environment Programming Guide.
CEEBXITA behaves differently depending on when it is invoked, as described in the following sections.