Function yyjson_mut_doc_set_str_pool_size 

pub unsafe extern "C" fn yyjson_mut_doc_set_str_pool_size(
    doc: *mut yyjson_mut_doc,
    len: usize,
) -> bool

Set the string pool size for a mutable document. This function does not allocate memory immediately, but uses the size when the next memory allocation is needed.

If the caller knows the approximate bytes of strings that the document needs to store (e.g. copy string with yyjson_mut_strcpy function), setting a larger size can avoid multiple memory allocations and improve performance.

@param doc The mutable document. @param len The desired string pool size in bytes (total string length). @return true if successful, false if size is 0 or overflow.