Format of APPC/PC "Change Number of Sessions" control block:
Offset	Size	Description	)
 00h 12 BYTEs	reserved
 0Ch	WORD	1500h (verb "Change Number of Sessions")
 0Eh  6 BYTEs	00h
 14h	WORD	(big-endian) primary return code (see #03681)
 16h	DWORD	(big-endian) secondary return code (see #03668,#03706)
 1Ah  8 BYTEs	(big-endian) logical unit ID
 22h  8 BYTEs	blanks
 2Ah  8 BYTEs	(big-endian) partner logical unit name
 32h  8 BYTEs	(big-endian) mode name
 3Ah	BYTE	bit 7: use MODE_NAME_SELECT_ALL rather than MODE_NAME
		bit 6: set negotiable values
 3Bh	BYTE	partner logical unit mode session limit
 3Ch	BYTE	minimum CONWINNERS_SOURCE
 3Dh	BYTE	maximum CONWINNERS_TARGET
 3Eh	BYTE	automatic activation
 3Fh	BYTE	00h
 40h	BYTE	flags
		bit 7: drain target
		bit 6: drain source
		bit 5: target responsible, not source