# YAML Function Settings

The `settings.functions` section configures how Atmos evaluates YAML functions in stack manifests.

## Configuration

**File:** `atmos.yaml`

```yaml
settings:
  functions:
    exec:
      max_concurrency: 1
```

## Sections

- **[`exec`](/cli/configuration/settings/functions/exec)**
  Set the maximum number of ordinary 
  `!exec`
   expressions that can run concurrently during a document evaluation.