CLAUDE_CODE_DECSTBM

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_DECSTBM is a Claude Code environment variable: Enables DECSTBM (VT100 Set Top and Bottom Margins) for scrolling regions in the TUI. The mechanism behind /tui fullscreen's flicker-free rendering — pins header and input while the middle region scrolls. Falls back to the tengu_marlin_porch gate when unset. Added between v2.1.108 and v2.1.114 and still present in v2.1.294. It is not in the official reference.

Status	Present in v2.1.294
Added	Added between v2.1.108 and v2.1.114
Category	Other
Official docs	Not listed

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_DECSTBM=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_DECSTBM": "<value>"
  }
}

Release notes that mention it

Claude Code v2.1.114 — Native Binary Launcher, /fewer-permission-prompts, and 20 New Environment Variables

Related variables

ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID
ANTHROPIC_WORKSPACE_ID
BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.
CLAUDE_AFK_COUNTDOWN_MS
CLAUDE_AI_ORIGIN: Overrides the base URL for Claude AI authentication endpoints.

Frequently asked questions

What does CLAUDE_CODE_DECSTBM do?

Enables DECSTBM (VT100 Set Top and Bottom Margins) for scrolling regions in the TUI. The mechanism behind /tui fullscreen's flicker-free rendering — pins header and input while the middle region scrolls. Falls back to the tengu_marlin_porch gate when unset.

Which Claude Code version has CLAUDE_CODE_DECSTBM?

Added between v2.1.108 and v2.1.114 and still present in v2.1.294.

How do I set CLAUDE_CODE_DECSTBM?

Export it before starting Claude Code (export CLAUDE_CODE_DECSTBM=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.