The system default buffer size of 512 bytes for pipe write
    operations can limit performance and generate extra line feeds
    when handling messages longer than 512 bytes.

    DECC$PIPE_BUFFER_SIZE allows a larger buffer size to be used for
    pipe functions such as pipe and popen. A value of 512 to 65535
    bytes can be specified.

    If DECC$PIPE_BUFFER_SIZE is not specified, the default buffer
    size 512 is used.

    Default: 512

    Minimum: 512

    Maximum: 65535