Extend_Quantity=number-blocks

    Sets the size, in blocks, by which the unload file (.unl) can
    be extended. The minimum value for the number-blocks parameter
    is 1; the maximum value is 65535. If you provide a value for the
    Allocation qualifier that is less than 65535, that value becomes
    the maximum you can specify.

    If you do not specify the Extend_Quantity qualifier, the default
    block size by which .unl files can be extended is 2048 blocks.