---
title: "PUT /2017-10-31/functions/{FunctionName}/concurrency"
method: PUT
path: "/2017-10-31/functions/{FunctionName}/concurrency"
---

# PUT /2017-10-31/functions/{FunctionName}/concurrency

`PUT /2017-10-31/functions/{FunctionName}/concurrency`

Sets the maximum number of simultaneous executions for a function, and reserves capacity for that concurrency level.

Concurrency settings apply to the function as a whole, including all published versions and the unpublished version. Reserving concurrency both ensures that your function has capacity to process the specified number of events simultaneously, and prevents it from scaling beyond that level. Use GetFunction to see the current setting for a function.

Use GetAccountSettings to see your Regional concurrency limit. You can reserve concurrency for as many functions as you like, as long as you leave at least 100 simultaneous executions unreserved for functions that aren't configured with a per-function limit. For more information, see [Lambda function scaling](https://docs.aws.amazon.com/lambda/latest/dg/invocation-scaling.html).

## Path parameters

- `FunctionName` string, required

## Request body

- object
  - `ReservedConcurrentExecutions` integer, required — The number of simultaneous executions to reserve for the function.

## Response `200`

Success

- Concurrency
  - `ReservedConcurrentExecutions` integer — The number of concurrent executions that are reserved for this function. For more information, see <a href="https://docs.aws.amazon.com/lambda/latest/dg/configuration-concurrency.html">Managing Lambda reserved concurrency</a>.

## Other responses

- `480` — ServiceException
- `481` — InvalidParameterValueException
- `482` — ResourceNotFoundException
- `483` — TooManyRequestsException
- `484` — ResourceConflictException

---

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