You set environment variables for MFFTP in the JCL-enabled enterprise server from within Enterprise Server Administration as follows:
[ES-Environment] MFFTP_var-name=var-value
You can use an optional ENVVAR DD statement to specify environment variable values. You add this in the JCL STEP that runs MFFTP. This can be a physical dataset or instream data, as in the example given in Running MFFTP. The advantage of using this approach is that the values pertain only to the current execution and override any values set within Enterprise Server Administration.
//ENVVAR DD * MFFTP_KEEP=Y