AFTSECT AFTSECT is used te describe a file currently open for a read or write. The AFT is created
when a file is opened. Space fer up to five AFTs is availatle in tMSNUC; any others must
reside in free storage. AFTSECT is invoked via the AFT macro.
Hexadecimal
o
8 10 60 68 70 78 80 88 90 98 AO Displacement
------------ 0 0 A4 A8 14C 150 1F4
1F8
29C 2AO 344 348 0 2 4 8
A
C 10 r--------------------------------------------------------,
AFTCLD AFTCLN AFTCLA
AFTDBD AFTDBN AFTDBA
AFTCLB
A*1 AFTPFST AFTIN AFTID
AFTFCLA AF'I'FCLX AFTCLDX A*2 1/////1 AFTOCLDX 1///////////////////////////
AFTD
AFTM AFTIC
AFTIL
AFTADT
Field
Name Xile AFT START DS OD DC 41F'0' DC A (*+4)
DC 41F'0' DC A (*+4)
DC 41F'0' DC A (*.4) DC 41F'0' DC A (*+4)
DC 41F'0' DC A (0) DC 2F'0' AFTCLD DS H
AFTCLN DS H
AFTCLA DS F
AFTDBD DS H
AFTDBN DS H
AFT DBA DS F
AFTCLB DS XL80 AFTN
AFTT AFTiP AFTRP
AFTFCL A*3 A*4 AFTtEC AFTYR AFTPTR
Field Description, Contents, First AFT l:lock Second AFT l:lock Third AFT block
Fourth AFT tlock
Fifth AFT block
Address of next AFT tlock (in free storage)
Reserved for IBM use Disk address of current chain link Numter of current chain link
Address of chain link buffer
Disk address of current data block
Number of current data block
Address of current data tlcck Chain link tuffer frcm first chain link Section 2. Data Areas and Contrel Blocks 143

lFTSECT Hexadecimal Field
Displacement Name 60 61
64
66
68 6C 6E 70 71
72
74
78
78 80 88 8C 8E 90 92
94
96
97
98 9C 9E AO A4
AFTFLG DS 1FT USED EQU AFTICF EQU AFTFBA EQU AFTDBF EQU AFTWRT EQU AFTRD EQU AFTFULD EQU AFTPFST DS AFTIN DS lFTID DS AFTFCLA DS AFTFCLX DS AFTCLDX DS AFTFLG2 DS AFT NEW EQU AFTOLDCL EQU AFTCLX EQU SA!UEN EQU DS AFTOCLDX DS DS f9EI 9! f§I AFTFST DS AFTN DS AFTT DS AFTD DS AFTWP DS AFTRP DS AFTM DS lFTIC DS AFTFCL DS AFTFV DS AFTFB DS AFTIL DS AFTDBC DS AFTYR DS AFTADT DS AFTPTR DS x
in AFTFLG --X'80'- X'40' X'20' X'10' X'08' X'04' X'02' X'01' 3X H
H
F
H
H X in AFTFLG2 --X'80'--- X'40' X'20' X'01' 1X 1H
F
D
D
F
H
H
H
H
H C X F
H
H
F
F in AFTPTR X'40'- lFTFSF EQU A8 DS OD AFTLB EQU *-AFTSECT AFTLD EQU AFTLB/8
Field Description, Contents, Meaning A*1 Flag l::yte
Active file table l::lock in use
Reserved for IMB use
First chain link in storage
Full l::uffer assigned
Data block in storage
Active write
Active read
Full disk special case Pointer to (static) FST entry Current item number
Displacement of current item in data block
Address of first chain link
Disk address of swapped FCl Disk address of swapped chain link
A*2 Seccnd flag byte New file Current chain link existed previously
Alternate chain link assigned/implied
Force same length update
Reserved for IBM use Old value (if any) of AFTCLDX Reserved for IBM use
Filename
Filetype
Date/time last written Write pointer (item no.)
Read pointer (item no.)
File.ode
Item count
First chain link
A*3 Fixed (F)/varial::le(V) flag
A*4 FST flag byte (Maximum) item length 800-l::yte data block count Year Pointer to active disk table Pointer to next AFT l::lock in chain
Indicates in free storage
End cf DSECT Length of AFT block in bytes
Length of AFT block in doul::lewords 144 IBM VM/370 Data Areas and Control Block Logic