When launching minecraft the following error message appears:
---- Minecraft Crash Report ----
// Shall we play a game?

Time: 24.01.15 13:32
Description: Initializing game

java.lang.OutOfMemoryError: Java heap space
at cue.a(SourceFile:363)
at cue.a(SourceFile:255)
at cua.b(SourceFile:130)
at cua.a(SourceFile:77)
at cxh.j(SourceFile:553)
at cxh.a(SourceFile:139)
at cxk.a(SourceFile:23)
at cvt.a(SourceFile:99)
at bss.ak(SourceFile:440)
at bss.a(SourceFile:302)
at net.minecraft.client.main.Main.main(SourceFile:124)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at cue.a(SourceFile:363)
at cue.a(SourceFile:255)
at cua.b(SourceFile:130)
at cua.a(SourceFile:77)
at cxh.j(SourceFile:553)
at cxh.a(SourceFile:139)
at cxk.a(SourceFile:23)
at cvt.a(SourceFile:99)
at bss.ak(SourceFile:440)

– Initialization –
Details:
Stacktrace:
at bss.a(SourceFile:302)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.8.1
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 67780760 bytes (64 MB) / 1060372480 bytes (1011 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.8.1
LWJGL: 2.9.1
OpenGL: GeForce GT 530/PCIe/SSE2 GL version 4.2.0, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: [Sphax PureBDcraft 512x MC17]
Current Language: Deutsch (Deutschland)
Profiler Position: N/A (disabled)