---
title: "JVM Heap Memory (-Xms and -Xmx) — Prism Launcher & Modded Minecraft Glossary"
description: "The minimum (`-Xms`) and maximum (`-Xmx`) system RAM in MiB that Java is allowed to allocate for Minecraft. Learn how JVM Heap Memory (-Xms and -Xmx) works in Prism Launcher on Windows."
canonical: https://prismlauncher.ink/words/jvm-heap-xmx-xms
updated: 2026-10-17
---

# JVM Heap Memory (-Xms and -Xmx)

The minimum (`-Xms`) and maximum (`-Xmx`) system RAM in MiB that Java is allowed to allocate for Minecraft.

## Facts (2026-10-17)

- **Term:** JVM Heap Memory (-Xms and -Xmx)
- **In Short:** The minimum (`-Xms`) and maximum (`-Xmx`) system RAM in MiB that Java is allowed to allocate for Minecraft.
- **Applies To:** Prism Launcher on Windows 10 & 11

## Definition: JVM Heap Memory (-Xms and -Xmx)

The minimum (`-Xms`) and maximum (`-Xmx`) system RAM in MiB that Java is allowed to allocate for Minecraft.

Configure memory globally in Prism Launcher Settings → Java or override it per instance under Edit Instance → Settings → Memory.

## How Prism Launcher handles this on Windows

Every instance in Prism Launcher exposes its version stack, mod list, resource packs, shader packs, and JVM settings in one clean Edit Instance window.

Grab the latest Windows installer or portable ZIP from [/download](https://prismlauncher.ink/download) to manage all your Minecraft versions in one place.

## FAQ

### What does JVM Heap Memory (-Xms and -Xmx) mean in Prism Launcher?

The minimum (`-Xms`) and maximum (`-Xmx`) system RAM in MiB that Java is allowed to allocate for Minecraft. Configure memory globally in Prism Launcher Settings → Java or override it per instance under Edit Instance → Settings → Memory.

### Where can I configure this inside the launcher?

Right-click any instance on the Prism Launcher dashboard and select **Edit** (or open global **Settings** on the top toolbar).

## Related

- [Prism Launcher Technical Glossary](https://prismlauncher.ink/words)
- [Prism Launcher Instance Management](https://prismlauncher.ink/instances)
- [Prism Launcher Java & JVM Configuration](https://prismlauncher.ink/java)
- [Prism Launcher Mod Loaders](https://prismlauncher.ink/loaders)
- [Instance (Isolated Minecraft Environment)](https://prismlauncher.ink/words/minecraft-instance)

## Download

Free and open source: [Download Prism Launcher](https://prismlauncher.ink/download)

Markdown mirror: https://prismlauncher.ink/words/jvm-heap-xmx-xms.md