z/OS Communications Server: SNA Programming
Previous topic | Next topic | Contents | Contact z/OS | Library | PDF


Request/response header (ISTRH)

z/OS Communications Server: SNA Programming
SC27-3674-00

Figure 1. Format of the RH
The diagram shows the format of the control block RH. The corresponding displacements are from 0 to 2 in decimal.
This note lists the meanings of the codes in the following table.
Note: Legend:
(Q)
Means applicable to a request header
(S)
Means applicable to a response header
(B)
Means applicable to either a request or response header.
 
 
Table 1. Request/response header DSECT (ISTRH)
DSECT label DSECT EQU label Field or EQU value For EQU: Meaning when bit setting on For DS: Meaning when byte value set Dec offset Hex offset
RH   XL3      
RHF0   X RH byte 0 0 0
  RHQS X'80' RH type indicator:
(Q) 0
request
(S) 1
response
 0 0
  RHQSREQ X'00' Request unit 0 0
  RHQSRSP X'80' Response unit 0 0
  RHRUCAT X'60' RU category indicator:
(B) 00
FM data
(B) 01
network control
(B) 10
data flow control
(B) 11
session control
 0 0
  RHFMD X'00' Function management data RU 0 0
  RHNC X'20' Network control RU 0 0
  RHDFC X'40' Data flow control RU 0 0
  RHSC X'60' Session control RU 0 0
  RHF0B3 X'10' (B) Reserved 0 0
  RHFI X'08' Format indicator:
(B) 0
no FM header, or character coded network services RU
(B) 1
FM header included, or field formatted network services RU
 0 0
  RHSDI X'04' Sense data included indicator:
(B) 0
sense data not included
(B) 1
sense data included
 0 0
  RHBCI X'02' Begin chain indicator:
(Q) 0
not beginning of chain
(B) 1
beginning of chain
 0 0
  RHECI X'01' End chain indicator:
(Q) 0
not end of chain
(B) 1
end of chain
 0 0
RHF1   X RH byte 1 1 1
  RHDR1 X'80' Definite response 1 indicator:
(Q) 0
definite response 1 not required
(Q) 1
definite response 1 required
(S) 0
not definite response 1
(S) 1
definite response
 1 1
  RHCI X'40' Compression indicator:
(Q) 0
RU is not compressed
(Q) 1
RU is compressed
(S)
reserved
 1 1
  RHDR2 X'20' Definite response 2 indicator:
(Q) 0
definite response 2 not required
(Q) 1
definite response 2 required
(S) 0
not definite response 2
(S) 1
definite response 2
 1 1
  RHERI X'10' Exception response indicator:
(Q) 0
definite or no response required
(Q) 1
exception response required
 1 1
  RHRTI X'10' (S) 0 positive response (S) 1 negative response 1 1
  RHF1B4 X'08' (B) Reserved 1 1
  RHRLWS X'04' Request larger window indicator:
(Q) 0
larger pacing window not requested
(Q) 1
larger pacing window requested
(S)
reserved
 1 1
  RHQRI X'02' Queued response indicator:
(B) 0
the response can flow ahead of the requests
(B) 1
the response cannot flow ahead of the requests
Note: The value of this field is set on a request and checked on the associated response.
 1 1
  RHPI X'01' Pacing indicator:
(B)
Reserved for VTAM® use
 1 1
RHF2   X RH byte 2 2 2
  RHBBI X'80' Begin bracket indicator:
(Q) 0
not begin bracket
(Q) 1
begin bracket
(S)
Reserved
 2 2
  RHEBI X'40' End bracket indicator:
(Q) 0
not end bracket
(Q) 1
end bracket
(S)
Reserved
 2 2
  RHCDI X'20' Change direction indicator:
(Q) 0
not change direction
(Q) 1
change direction
(S)
Reserved
 2 2
  RHF2B3 X'10' (B) Reserved 2 2
  RHCSI X'08' Code selection indicator:
(Q) 0
code 0
(Q) 1
code 1
(S)
Reserved
 2 2
  RHEDI X'04' Enciphered data indicator:
(Q) 0
data is not enciphered
(Q) 1
data is enciphered
(S)
Reserved
 2 2
  RHPDI        
  RHPRI X'02' Padded data indicator:
(B)
Reserved for VTAM use
 2 2
  RHCEBI X'01' Conditional end bracket indicator:
(Q) 0
not conditional end bracket
(Q) 1
conditional end bracket
(S)
Reserved
 2 2
Parent topic: Control block formats and DSECTs

Go to the previous page Go to the next page

Notices | Terms of use | Support | Contact z/OS | zFavorites



Copyright IBM Corporation 1990, 2014