# Class ExternalConfigLarge
Large size type configuration for the ExternalString.

Defined in | <seqan/file.h>
Signature | `template <[typename TFile[, unsigned SEQAN_PAGESIZE[, unsigned FRAMES]]> struct ExternalConfigLarge;`

## Template Parameters

`TFile` | The File type to use. Default: `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.

## Detailed Description

### Remarks

When using this configuration ,the `Size` type of the ExternalString is `Size` type of `TFile`. Normally, this is a 64 bit integer. For a smaller size type use ExternalConfig.

Some data structures store size types values (e.g. suffix arrays in indices). To save memory, you should think o fusing ExternalConfig.

## See Also

- ExternalConfig

#### Dox Sources

    /*!
     * @class ExternalConfigLarge
     *
     * @headerfile <seqan/file.h>
     *
     * @brief Large size type configuration for the @link ExternalString @endlink.
     *
     * @signature template <[typename TFile[, unsigned SEQAN_PAGESIZE[, unsigned
     *            FRAMES]]> struct ExternalConfigLarge;
     *
     * @tparam TFile The @link File @endlink type to use. Default:
     *               <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.
     *
     * @section Remarks
     *
     * When using this configuration ,the <tt>Size</tt> type of the ExternalString
     * is <tt>Size</tt> type of <tt>TFile</tt>. Normally, this is a 64 bit integer.
     * For a smaller size type use ExternalConfig.
     *
     * Some data structures store size types values (e.g. suffix arrays in indices).
     * To save memory, you should think o fusing ExternalConfig.
     *
     * @see ExternalConfig
     */