# Class ExternalConfigSize
Arbitrary size type configuration for ExternalString.

Defined in | <seqan/file.h>
Signature | `template <typename TSize[, typename TFile[, unsigned SEQAN_PAGESIZE[, unsigned FRAMEs]]]> class ExternalConfigSize;`

## Template Parameters

`TSize` | The size type of the ExternalString.
`TFile` | Type of file the ExternalString will be based on. Defaults to `File<>`.
`SEQAN_PAGESIZE` | The number of values in one page. This should be a power of 2 to speed up transfer and calculations. Default: 220.
`FRAMES` | The number of pages that should reside in internal memory. To enable prefetching and automatic swap-out, `frames` should be greater than 1. Default: 2.

#### Dox Sources

    /*!
     * @class ExternalConfigSize
     *
     * @headerfile <seqan/file.h>
     *
     * @brief Arbitrary size type configuration for @link ExternalString @endlink.
     *
     * @signature template <typename TSize[, typename TFile[, unsigned
     *            SEQAN_PAGESIZE[, unsigned FRAMEs]]]> class ExternalConfigSize;
     *
     * @tparam TSize The size type of the ExternalString.
     * @tparam TFile Type of file the ExternalString will be based on. Defaults to
     *               <tt>File&lt;&gt;</tt>.
     * @tparam SEQAN_PAGESIZE The number of values in one page. This should be a
     *                        power of 2 to speed up transfer and calculations.
     *                        Default: 2<sup>20</sup>.
     * @tparam FRAMES The number of pages that should reside in internal memory. To
     *                enable prefetching and automatic swap-out, <tt>frames</tt>
     *                should be greater than 1. Default: 2.
     */