How to divide screen into three parts vertically?

I have screen with ScrollView and three different LinearLayouts.

One LinearLayout contains a Spinner and second contains ListView and third contains two Buttons ( horizontal ).

I want to display a screen that contains 3 LinearLayouts always displayed at bottom of screen and 1 LinearLayout always displayed on top. In middle part , i want to display ListView content. So that on whole screen there is no blank space present.

I want to create screen for multiple devices which has different sizes.

     <?xml version="1.0" encoding="utf-8"?>
     <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/backrepeat"
android:orientation="vertical" >

<include
    android:id="@+id/include1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    layout="@layout/actionbar" >
</include>

<ScrollView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:scrollbars="horizontal" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical"
        android:padding="10dp" >

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight=".2"
            android:background="@drawable/rounded_border"
            android:orientation="vertical"
            android:padding="15dp" >

            <TextView
                android:id="@+id/tvDiaryData"
                style="@style/greenstyle"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:background="@drawab