# Local Stacks

A Stack defines a set of platform configuration options that will get
applied to each Node-RED instance when it is created.

For the Local deployment model, this covers two things:

- `memory` - the value to apply (in MB) to the Node.js `max-old-space-size` option.
This defines the point where Node.js will start freeing unused memory. It is
not a hard limit - Node-RED's memory usage will not be capped - but this
is useful when running on a memory constrained device such as a Raspberry Pi. Recommended minimum `256`.
- `nodered` - the version number of Node-RED to use. This should match the value used in the steps following.

The FlowFuse installer will create a default stack using the latest stable
release of Node-RED.

The stacks are stored under `/opt/flowforge/var/stacks` or `c:\flowforge\var\stacks` on Windows.

### Creating a Stack

When a new version of Node-RED is released, it can be added to your FlowFuse
platform by creating a new stack.

For a local install there are two steps required:

1. Install a new Node-RED version<br />

In the FlowFuse Home directory, run the provided install script. You
must provide the full Node-RED version number, eg `3.0.2`, or use `latest` to install the most recent stable version.<br />

Linux/Mac:```bash
cd /opt/flowforge
./bin/ff-install-stack.sh 3.0.2
```

<br />

Windows```bash
cd c:\flowforge
bin\ff-install-stack.bat 3.0.2
```
2. Add the Stack into the FlowFuse Admin UI - see [Managing Stacks](/docs/admin/introduction/#managing-stacks).

### Development Only

If you are developing FlowFuse having checked it out from GitHub then you can run
the following command in the repository root to install a stack:

```bash
npm run install-stack --vers=3.0.2
```