DFSCNC40 (I/O request DIE routine)

The only modules that manipulate the LXB trace stack are the CTC access method modules, DFSCMC00, DFSCMC10, DFSCMC40, and DFSCMC50. The values and meaning of DFSCNC40 are listed.

Byte 1, bits 4-7

Value: Meaning
0: Second entry into this routine was taken; nothing was done
1: LXBCLIB switch was reset
2: IOSB on queue was modified to perform a WRITE operation (this is always a 1-byte entry)