RAM Allocation (Minimum & Maximum Memory MiB)

Setting Maximum Memory too low causes OutOfMemory freezes, while setting it above 10–12 GB can cause long garbage-collection lag spikes. Applies to All Minecraft versions.

Configuration

RAM Allocation (Minimum & Maximum Memory MiB)

Minecraft Range

All Minecraft versions

Recommended Build

Prism Launcher Settings → Java → Memory

JVM Flags

-Xms1024m -Xmx4096m (Vanilla/Fabric) or -Xmx8192m (Heavy Modpacks)

Why RAM Allocation (Minimum & Maximum Memory MiB) matters for All Minecraft versions

Setting Maximum Memory too low causes OutOfMemory freezes, while setting it above 10–12 GB can cause long garbage-collection lag spikes.

Inside Prism Launcher, open **Settings** → **Java** (or override per instance under **Edit Instance** → **Settings**) and click **Auto-detect** or **Download** to select `Prism Launcher Settings → Java → Memory`.

Recommended JVM flags and memory checks

• **JVM arguments:** `-Xms1024m -Xmx4096m (Vanilla/Fabric) or -Xmx8192m (Heavy Modpacks)`. Always click **Test** in the Java settings panel to verify the runtime passes Prism's architecture check.
• **64-bit verification:** Ensure the architecture column reads `x86_64` (or `arm64`), never 32-bit `x86`, so you can allocate more than 2 GB of RAM.
• **Download launcher:** Get the latest Windows build of Prism Launcher from /download.