Changes in default memory

Increased Default Maximum Memory to 200Mb
Added config.xml for the heat transfer example for memory management
(among other parameters) at runtime 

To do:
Copy config.xml to /build/bin, right now the heat transfer example won't
run in config.xml is not found

examples/heatTransfer/write/config.xml

+<?xml version="1.0"?>
+<!-- Config XML file fo the  heatTransfer_write_adios2 executable from 
+     IO_adios2.cpp -->
+
+<adios-config>
+    <io name="output">
+        <engine type="BPFileWriter">
+            
+            <!-- for vectorized memory operations --> 
+            <parameter key="Threads" value="1"/>
+
+            <!-- Microseconds (default), Milliseconds, Seconds, 
+                 Minutes, Hours -->
+            <parameter key="ProfileUnits" value="Microseconds"/>
+
+            <!-- XXKb, XXMb, or XXXGb supported, default=16Kb 
+                (applications might choose an optimal value) -->
+            <parameter key="InitialBufferSize" value="1Mb"/>
+            
+            <!-- XXKb, XXMb, or XXXGb supported, default=200Mb 
+                (applications might choose an optimal value) -->
+            <parameter key="MaxBufferSize" value="20Mb"/>
+
+            <!-- exponential growth factor > 1, default = 2 (as in the STL) 
+                 for this case: 1, 2, 4, 8, 16, 20 Mb -->
+            <parameter key="BufferGrowthFactor" value="2"/>
+            
+        </engine>
+
+        <transport type="File">
+            
+            <!-- POSIX, stdio (C FILE*), fstream (C++) -->
+            <parameter key="Library" value="POSIX"/>
+            
+            <!-- For read/write, Microseconds (default), Milliseconds, Seconds, 
+                 Minutes, Hours. open/close always in Microseconds -->
+            <parameter key="ProfileUnits" value="Milliseconds"/>
+        </transport>
+    </io>
+</adios-config>

source/adios2/ADIOSTypes.h

@@ -2,7 +2,8 @@
  * Distributed under the OSI-approved Apache License, Version 2.0.  See
  * accompanying file Copyright.txt for details.
  *
- * ADIOSTypes.h
+ * ADIOSTypes.h : public header that contains "using/typedef" alias, defaults
+ * and parameters options as enum classes
  *
  *  Created on: Mar 23, 2017
  *      Author: Chuck Atkins chuck.atkins@kitware.com
@@ -31,7 +32,8 @@
 namespace adios2
 {
 
-/** Variable shape type identifier */
+/** Variable shape type identifier, assigned automatically from the signature of
+ *  DefineVariable */
 enum class ShapeID
 {
     GlobalValue, ///< single global value, common case
@@ -84,12 +86,12 @@ enum class TransportType
     WAN
 };
 
-/** Just for info purposes */
+/** Currently available engines, just for info purposes */
 enum class IOEngine
 {
     Unknown,
     BPFileWriter, ///< produces bp files
-    BPFileReader, ///< read bp files
+    BPFileReader, ///< read bp files (not yet implemented)
     HDF5Writer,   ///<
     HDF5Reader,   ///<
     ADIOS1Writer,
@@ -151,13 +153,18 @@ constexpr TimeUnit DefaultTimeUnitEnum(TimeUnit::Microseconds);
 
 /** default initial bp buffer size, 16Kb, in bytes */
 constexpr size_t DefaultInitialBufferSize(16384);
-/** default maximum bp buffer size, 16Mb, in bytes */
-constexpr size_t DefaultMaxBufferSize(16777216);
-/** default buffer growth factor (from STL vector = 2.) */
+
+/** default maximum bp buffer size, 250Mb, in bytes.
+ *  Needs to be studied for optimizing applications */
+constexpr size_t DefaultMaxBufferSize(268435456000);
+
+/** default buffer growth factor (from STL vector = 2.). Needs to be studied
+ * for optimizing applications*/
 constexpr float DefaultBufferGrowthFactor(2.);
+
 /** default size for writing/reading files using POSIX/fstream/stdio write
- *  1Gb - 1Kb (tolerance)*/
-constexpr size_t DefaultMaxFileBatchSize(1024 * 1024 * 1024 - 1024);
+ *  2Gb - 100Kb (tolerance)*/
+constexpr size_t DefaultMaxFileBatchSize(2 * 1024 * 1024 * 1024 - 100 * 1024);
 
 // adios alias values and types
 constexpr bool DebugON = true;