| Parameter | Meaning and Use | Valid Range | Default Value |
| BUFSIZE | Specifies the storage size of a TIOC buffer. | 20-252 | 64 |
| BUFFERS | Specifies the number of buffers in the TIOC buffer pool. | 4-32,768 | six times the USERMAX value |
| INLOCKHI | Specifies the number of TIOC buffers to be allocated to a terminal user for input before his keyboard is locked. INLOCKHI must be large enough to permit TIOC to receive the largest possible legitimate input message sent from any terminal in the system. | 1-32,768 | 4 |
| INLOCKLO | Specifies a low threshold of allocated input buffers. When the number of allocated input buffers is reduced to or below this number, the user's keyboard is unlocked. | less than INLOCKHI and BUFFERS | 1 |
| OWAITHI | Specifies the maximum number of output buffers than can be allocated to a terminal. When that number is reached, the users' address space is placed in output wait and is swapped out of real storage. | 1-32,767 | 20 |
| OWAITLO | Specifies a low threshold value for the number of allocated output buffers. When the number of output buffers reaches this value, the system resource manager is notified that the terminal user's job can be swapped into storage and allowed to execute. | less than OWAITHI and BUFFERS | 4 |
| RECONLIM | Specifies the time limit in minutes within which a user may reconnect after his TP line has been disconnected. | 0-32,767 | 0 |
| RESVBUF | Specifies the minimum number of free buffers that are available. Its purpose is to maintain a reserve of free buffers that can handle output without bottlenecking the system. If the number of free buffers falls below this value, all terminals are locked for input, regardless of INLOCKHI value. The terminals will be unlocked when the number of free buffers becomes equal to RESVBUF. | 1 - value of BUFFERS | 10% of the number of buffers specified in BUFFERS parameter. |
| USERMAX | Specifies the maximum number of time sharing users that may be logged on. | 1-32,767 | Total number of terminals that support time sharing plus 10%. |