max_bars_back() - Pine Script Function

max_bars_back()

Overview

max_bars_back() tells Pine how many historical bars to retain for a specific series or object. Use it when a history reference such as series[dynamicIndex] depends on runtime data that Pine cannot predict at compile time. Without an explicit buffer size the script may throw a runtime error once it asks for more history than is available.

The num argument must be a compile-time constant. Choose a value that comfortably exceeds the largest dynamic offset you expect, but avoid inflating it unnecessarily because large buffers increase memory usage.

Syntax

max_bars_back(var, num) → void

Parameters

Name	Type	Description
var	series int/float/bool/color/label/line	Identifier of the series or object you will index dynamically.
num	const int	Maximum number of historical bars Pine should retain for var.

Remarks

• Call max_bars_back() before the first place you index the target series with a variable offset.
• Built-ins such as hl2 or ohlc4 are derived values; apply max_bars_back() to their components (high, low, etc.) instead.
• Prefer the function to the global indicator(..., max_bars_back=...) parameter when only a single series requires manual buffering; it keeps memory usage in check.

Example

//@version=5
indicator("Dynamic lookback pivot", overlay=false)

const int MAX_LOOKBACK = 800
max_bars_back(close, MAX_LOOKBACK)

lookback = input.int(150, "Bars back", minval=1, maxval=MAX_LOOKBACK - 1)
offset = math.min(lookback, bar_index)

pivotClose = na
if bar_index >= offset
    pivotClose := close[offset]

plot(close, "Close", color=color.gray)
plot(pivotClose, "Close at bars-back offset", color=color.orange)

bgcolor(bar_index < offset ? color.new(color.red, 90) : na,
    title="Insufficient history warning")

See Also

• indicator()
• strategy()
• nz()
• fixnan()