How many usage of OCIThreadInit() in multiple OCI Environment ?

 Hello,

OCI doc says:

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The first time OCIThreadInit() is called, it initializes the OCI Thread context. It also saves a pointer to the context in some system dependent manner. Subsequent calls to OCIThreadInit() will return the same context.

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If I have multiple thread that each has its own OCI Environment Handle, do I have to call OCIThreadInit() for each OCI Environment Handle ? Or, is calling it once enough ?

thanks in advance...