diff --git a/.travis.yml b/.travis.yml
index 123739b..5e42406 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,7 +12,7 @@ before_cache:
 script:
   - |
     rustc --version &&
-    cargo test
+    cargo test --all-features
 matrix:
   allow_failures:
     - rust: nightly
diff --git a/README.md b/README.md
index f7d8039..51af513 100644
--- a/README.md
+++ b/README.md
@@ -43,14 +43,16 @@ config! {
     ),
     
     APP {
+        static BASE_URL => "/api", // &'static str by default
+    
         ARTICLE {
-            PER_PAGE: u32 => 15,
+            static PER_PAGE: u32 => 15,
         }
         
         #[cfg(feature = "companies")]
         COMPANY {
             #[env_name = "INSTITUTIONS_PER_PAGE"]
-            PER_PAGE: u32 => 15,
+            static PER_PAGE: u32 => 15,
         }
     }
     
@@ -117,30 +119,30 @@ cargo test
 
 ## Available features
 
-* default = ["macro", "primitives"]
-* macro = []
-* array = ["serde_json"]
-* primitives = ["numbers", "bool"]
-* numbers = ["int", "uint", "float"]
-* int = ["i8", "i16", "i32", "i64", "i128", "isize"]
-* uint = ["u8", "u16", "u32", "u64", "u128", "usize"]
-* float = ["f32", "f64"]
-* i8    = []
-* i16   = []
-* i32   = []
-* i64   = []
-* i128  = []
-* isize = []
-* u8    = []
-* u16   = []
-* u32   = []
-* u64   = []
-* u128  = []
-* usize = []
-* f32   = []
-* f64   = []
-* bool  = []
-
+* **default** - ["macro", "primitives"]
+* **macro** - Activates `config!` macros for easy configure web application.
+* **static** - Add `static` option to `config!` macros (uses optional `lazy_static` package).
+* **array** - Add EnvString impl for vector type (uses optional `serde_json` package).
+* **primitives** - Group for features: `numbers` and `bool`.
+* **numbers** - Group for features: `int`, `uint` and `float`.
+* **int** - Group for features: `i8`, `i16`, `i32`, `i64`, `i128` and `isize`.
+* **uint** - Group for features: `u8`, `u16`, `u32`, `u64`, `u128` and `usize`.
+* **float** - Group for features: `f32` and `f64`
+* **i8** - impl EnvString for i8 type
+* **i16** - impl EnvString for i16 type
+* **i32** - impl EnvString for i32 type
+* **i64** - impl EnvString for i64 type
+* **i128** - impl EnvString for i128 type
+* **isize** - impl EnvString for isize type
+* **u8** - impl EnvString for u8 type
+* **u16** - impl EnvString for u16 type
+* **u32** - impl EnvString for u32 type
+* **u64** - impl EnvString for u64 type
+* **u128** - impl EnvString for u128 type
+* **usize** - impl EnvString for usize type
+* **f32** - impl EnvString for f32 type
+* **f64** - impl EnvString for f64 type
+* **bool** - impl EnvString for bool type
 
 ## License
 
diff --git a/itconfig/Cargo.toml b/itconfig/Cargo.toml
index 6e92a30..6d39480 100644
--- a/itconfig/Cargo.toml
+++ b/itconfig/Cargo.toml
@@ -20,7 +20,7 @@ lazy_static = { version = "1.4.0", optional = true }
 serde_json = { version = "1.0.44", optional = true }
 
 [features]
-default = ["macro", "primitives", "static"]
+default = ["macro", "primitives"]
 
 macro = []
 static = ["lazy_static"]
diff --git a/itconfig/README.md b/itconfig/README.md
index e751c66..6af0f83 100644
--- a/itconfig/README.md
+++ b/itconfig/README.md
@@ -30,14 +30,16 @@ config! {
     ),
     
     APP {
+        static BASE_URL => "/api", // &'static str by default
+    
         ARTICLE {
-            PER_PAGE: u32 => 15,
+            static PER_PAGE: u32 => 15,
         }
         
         #[cfg(feature = "companies")]
         COMPANY {
             #[env_name = "INSTITUTIONS_PER_PAGE"]
-            PER_PAGE: u32 => 15,
+            static PER_PAGE: u32 => 15,
         }
     }
     
@@ -98,29 +100,30 @@ fn main() {
 
 ## Available features
 
-* default = ["macro", "primitives"]
-* macro = []
-* array = ["serde_json"]
-* primitives = ["numbers", "bool"]
-* numbers = ["int", "uint", "float"]
-* int = ["i8", "i16", "i32", "i64", "i128", "isize"]
-* uint = ["u8", "u16", "u32", "u64", "u128", "usize"]
-* float = ["f32", "f64"]
-* i8    = []
-* i16   = []
-* i32   = []
-* i64   = []
-* i128  = []
-* isize = []
-* u8    = []
-* u16   = []
-* u32   = []
-* u64   = []
-* u128  = []
-* usize = []
-* f32   = []
-* f64   = []
-* bool  = []
+* **default** - ["macro", "primitives"]
+* **macro** - Activates `config!` macros for easy configure web application.
+* **static** - Add `static` option to `config!` macros (uses optional `lazy_static` package).
+* **array** - Add EnvString impl for vector type (uses optional `serde_json` package).
+* **primitives** - Group for features: `numbers` and `bool`.
+* **numbers** - Group for features: `int`, `uint` and `float`.
+* **int** - Group for features: `i8`, `i16`, `i32`, `i64`, `i128` and `isize`.
+* **uint** - Group for features: `u8`, `u16`, `u32`, `u64`, `u128` and `usize`.
+* **float** - Group for features: `f32` and `f64`
+* **i8** - impl EnvString for i8 type
+* **i16** - impl EnvString for i16 type
+* **i32** - impl EnvString for i32 type
+* **i64** - impl EnvString for i64 type
+* **i128** - impl EnvString for i128 type
+* **isize** - impl EnvString for isize type
+* **u8** - impl EnvString for u8 type
+* **u16** - impl EnvString for u16 type
+* **u32** - impl EnvString for u32 type
+* **u64** - impl EnvString for u64 type
+* **u128** - impl EnvString for u128 type
+* **usize** - impl EnvString for usize type
+* **f32** - impl EnvString for f32 type
+* **f64** - impl EnvString for f64 type
+* **bool** - impl EnvString for bool type
 
 
 ## License
diff --git a/itconfig/src/envstr.rs b/itconfig/src/envstr.rs
index c46a1b2..b20e343 100644
--- a/itconfig/src/envstr.rs
+++ b/itconfig/src/envstr.rs
@@ -76,6 +76,7 @@ impl FromEnvString for bool {
 
 
 #[cfg(feature = "array")]
+#[derive(Debug)]
 pub enum ArrayEnvError {
     InvalidType,
     FailedToParse,
diff --git a/itconfig/src/lib.rs b/itconfig/src/lib.rs
index 56cfe99..e260566 100644
--- a/itconfig/src/lib.rs
+++ b/itconfig/src/lib.rs
@@ -35,14 +35,16 @@
 //!     ),
 //!
 //!     APP {
+//!         static BASE_URL => "/api", // &'static str by default
+//!
 //!         ARTICLE {
-//!             PER_PAGE: u32 => 15,
+//!             static PER_PAGE: u32 => 15,
 //!         }
 //!
 //!         #[cfg(feature = "companies")]
 //!         COMPANY {
 //!             #[env_name = "INSTITUTIONS_PER_PAGE"]
-//!             PER_PAGE: u32 => 15,
+//!             static PER_PAGE: u32 => 15,
 //!         }
 //!     }
 //!
@@ -62,6 +64,7 @@
 //!     cfg::init();
 //!     assert_eq!(cfg::HOST(), String::from("127.0.0.1"));
 //!     assert_eq!(cfg::DATABASE_URL(), String::from("postgres://user:pass@localhost:5432/test"));
+//!     assert_eq!(cfg::APP::BASE_URL(), "/api");
 //!     assert_eq!(cfg::APP::ARTICLE::PER_PAGE(), 15);
 //!     assert_eq!(cfg::FEATURE::NEW_MENU(), true);
 //! }
@@ -84,10 +87,43 @@
 //! }
 //! ```
 //!
+//! ## Available features
+//!
+//! * **default** - ["macro", "primitives"]
+//! * **macro** - Activates `config!` macros for easy configure web application.
+//! * **static** - Add `static` option to `config!` macros (uses optional `lazy_static` package).
+//! * **array** - Add EnvString impl for vector type (uses optional `serde_json` package).
+//! * **primitives** - Group for features: `numbers` and `bool`.
+//! * **numbers** - Group for features: `int`, `uint` and `float`.
+//! * **int** - Group for features: `i8`, `i16`, `i32`, `i64`, `i128` and `isize`.
+//! * **uint** - Group for features: `u8`, `u16`, `u32`, `u64`, `u128` and `usize`.
+//! * **float** - Group for features: `f32` and `f64`
+//! * **i8** - impl EnvString for i8 type
+//! * **i16** - impl EnvString for i16 type
+//! * **i32** - impl EnvString for i32 type
+//! * **i64** - impl EnvString for i64 type
+//! * **i128** - impl EnvString for i128 type
+//! * **isize** - impl EnvString for isize type
+//! * **u8** - impl EnvString for u8 type
+//! * **u16** - impl EnvString for u16 type
+//! * **u32** - impl EnvString for u32 type
+//! * **u64** - impl EnvString for u64 type
+//! * **u128** - impl EnvString for u128 type
+//! * **usize** - impl EnvString for usize type
+//! * **f32** - impl EnvString for f32 type
+//! * **f64** - impl EnvString for f64 type
+//! * **bool** - impl EnvString for bool type
+//!a
 
 
 // Rustc lints.
-//#![deny(unused_imports)]
+#![deny(
+    missing_debug_implementations,
+    unsafe_code,
+    unstable_features,
+    unused_imports,
+    unused_qualifications,
+)]
 
 /////////////////////////////////////////////////////////////////////////////
 
diff --git a/itconfig/src/macro.rs b/itconfig/src/macro.rs
index 47118f5..a4b7a84 100644
--- a/itconfig/src/macro.rs
+++ b/itconfig/src/macro.rs
@@ -203,6 +203,49 @@
 /// cfg::init();
 /// ```
 ///
+/// Static
+/// ------
+///
+/// `with feauter = "static"`
+///
+/// Starting with 0.11 version you can use lazy static for improve speed of variable. This is very
+/// useful, if you use variable more than once.
+///
+/// ```rust
+/// # #[macro_use] extern crate itconfig;
+/// # use std::env;
+/// env::set_var("APP_BASE_URL", "/api/v1");
+///
+/// config! {
+///     static APP_BASE_URL => "/api",
+/// }
+///
+/// cfg::init();
+/// assert_eq!(cfg::APP_BASE_URL(), "/api/v1");
+/// ```
+///
+/// You also can use static with concat variables
+///
+/// ```rust
+/// # #[macro_use] extern crate itconfig;
+/// config! {
+///     static CONNECTION_STRING < (
+///         "postgres://",
+///         NOT_DEFINED_PG_USERNAME => "user",
+///         ":",
+///         NOT_DEFINED_PG_PASSWORD => "pass",
+///         "@",
+///         NOT_DEFINED_PG_HOST => "localhost:5432",
+///         "/",
+///         NOT_DEFINED_PG_DB => "test",
+///     ),
+/// }
+///
+/// cfg::init();
+/// assert_eq!(cfg::CONNECTION_STRING(), "postgres://user:pass@localhost:5432/test".to_string());
+/// ```
+///
+///
 /// ---
 ///
 /// This module will also contain helper method:
@@ -258,6 +301,14 @@ macro_rules! __itconfig_invalid_syntax {
             `https://docs.rs/itconfig/latest/itconfig/macro.config.html`"
         );
     };
+
+    (feature "static") => {
+        compile_error!(
+            "Feature `static` is required for enable this macro function.\
+            Please see the `config!` macro docs for more info.\
+            `https://docs.rs/itconfig/latest/itconfig/macro.config.html`"
+        );
+    };
 }
 
 #[macro_export]
@@ -346,6 +397,7 @@ macro_rules! __itconfig_parse_variables {
         ],
         $($args:tt)*
     ) => {
+        #[cfg(feature = "static")]
         __itconfig_parse_variables! {
             current_variable = {
                 unparsed_meta = [$(#$meta)*],
@@ -359,6 +411,9 @@ macro_rules! __itconfig_parse_variables {
             tokens = [$($rest)*],
             $($args)*
         }
+
+        #[cfg(not(feature = "static"))]
+        __itconfig_invalid_syntax!(feature "static");
     };
 
     // Find concatenated variable
@@ -394,6 +449,7 @@ macro_rules! __itconfig_parse_variables {
         ],
         $($args:tt)*
     ) => {
+        #[cfg(feature = "static")]
         __itconfig_parse_variables! {
             current_variable = {
                 unparsed_meta = [$(#$meta)*],
@@ -408,6 +464,9 @@ macro_rules! __itconfig_parse_variables {
             tokens = [$($rest)*],
             $($args)*
         }
+
+        #[cfg(not(feature = "static"))]
+        __itconfig_invalid_syntax!(feature "static");
     };
 
     // Find variable