X SYSTEM: Keyboard locked by the host

What it means

The bottom line of a 3270 screen is the operator information area (OIA). An X near the left of it means input is inhibited, so the keyboard won't accept typing. The word after the X says why. SYSTEM means the lock came from the host side, not from something you typed.

A 3270 screen works in turns. You fill in fields and press Enter, a PF key, a PA key or Clear. Those keys send the screen to the host, and the keyboard locks. It stays locked until the application sends something back with the keyboard restore bit set in the write control character (WCC) of its output. If the application is slow, waiting on a database lock, or never writes back at all, the lock stays and so does X SYSTEM.

Exactly when an emulator shows X SYSTEM rather than the clock symbol varies by product and by how the session is connected. Both mean the same thing for the operator. The host owns the keyboard right now.

Common causes

• The transaction is still running. A long query, a large file read or a batch-style request started from a screen can keep the keyboard locked for many seconds.
• The application is waiting for something else, such as a Db2 or VSAM record another user holds, an MQ reply or a remote system.
• The application sent output but left the keyboard restore bit off in the WCC, so the screen changed but the keyboard stayed locked.
• The transaction ended abnormally after you pressed Enter and nothing was sent back to the terminal.
• The network or the TN3270 connection stalled after the screen was sent, so the reply never arrived.

How to find the problem

1. Note the time and which key you pressed. If several people see X SYSTEM in the same application at the same time, the problem is on the host side.
2. Check whether the clock or SYSTEM indicator clears by itself within a minute. If it does, the transaction is just slow, and the support team can look at response time.
3. In CICS, the support team can look for your task with CEMT INQUIRE TASK and see whether it is suspended and on what. In IMS, /DISPLAY commands show whether the transaction is queued or stopped.
4. Watch the status line. If X SYSTEM gives way to COMM and a number, the connection is the problem, not the application.
5. A programmer can trace the outbound data stream and check the WCC byte that follows the write command. If bit 6 (keyboard restore) is off, the application left the keyboard locked on purpose or by mistake.

How to fix it

• Wait. Most X SYSTEM locks clear on their own when the host answers.
• If it doesn't clear after a reasonable time, press the Attn key or PA1 if your application uses them to interrupt, or ask the support team to purge the task. Pressing Reset does not hurry the host along.
• If the session is hung for good, disconnect and reconnect the emulator session. Any input you sent may or may not have been processed, so check the result before you repeat an update.
• Programmers should set keyboard restore on the last screen of every response. In CICS BMS that is the FREEKB option on SEND MAP or SEND TEXT. A raw data stream needs bit 6 of the WCC set.
• If the lock always follows one transaction, ask the application team to look for a missing response, a long wait on a resource or an abend that ends the task before it writes.

Technical reviewer: Albert Joseph, WND Software.

Last reviewed 2026-10-18 by the WND Software team. Written in our own words. For the full reference, check IBM’s 3270 or 5250 display documentation.