# xSQL Runtime Options Settings

> The xSQL configuration file can be used to define a number of parameters that correspond to eXtremeDB runtime options (set in C API applications by calling `mco_runtime_setoption()`).

> ### For an overview see page Configuration File Parameters

> The `runtime_options` section consists of a set of "name : value" pairs enclosed within braces. For example:

>         runtime_options : {
>             posix_shm_opt : [anonymous, shared]
>         },

>         ...

> The following tables define the possible options for the `runtime_options` section of the configuration file (the corresponding C API option value is specified in the comment):

> Option name : example value | Comment
> --- | ---
> extheaps : 1, | `MCO_RT_OPTION_EXTHEAPS`, unsigned
> windows_shm_opt : {...} | `MCO_RT_WINDOWS_SHM_OPT`
> Option name : example value | Comment
> --- | ---
> prefix : none, | One of : `global` (`MCO_RT_WINDOWS_SHM_PREFIX_GLOBAL`), `local` (`MCO_RT_WINDOWS_SHM_PREFIX_LOCAL`), `sessions` (`MCO_RT_WINDOWS_SHM_PREFIX_SESSIONS`) `none` (`MCO_RT_WINDOWS_SHM_PREFIX_NONE)`
> sec_descr : empty, | One of : `empty` (`MCO_RT_WINDOWS_SHM_SEC_DESCR_EMPTY`), `null` (`MCO_RT_WINDOWS_SHM_SEC_DESCR_NULL`) or `sameuser` (`MCO_RT_WINDOWS_SHM_SEC_DESCR_SAMEUSER`)
> mark_last_obj : true, | `MCO_RT_OPTION_MARK_LAST_OBJ`, boolean
> unix_shm_mask : 0666, | `MCO_RT_OPTION_UNIX_SHM_MASK`, unsigned
> posix_shm_opt : [anonymous, shared] | `MCO_RT_POSIX_SHM_OPT`, combination of `anonymous` (`MCO_RT_POSIX_SHM_ANONYMOUS`) and `shared` (`MCO_RT_POSIX_SHM_SHARED`)
> crc_algorithm | `MCO_RT_CRC_ALGORITHM`
> max_patricia_depth | `MCO_RT_MAX_PATRICIA_DEPTH`
> max_dynamic_pipes | `MCO_RT_MAX_DYNAMIC_PIPES`
> class_load_merge | `MCO_RT_OPTION_CLASS_LOAD_MERGE`
> datetime_precision | `MCO_RT_OPTION_DATETIME_PRECISION`