EDTAMCB - Access method control block

EDTAMCB (Access Method Control Block) is the control block for the logical record access functions. It contains the data fields which are required to access the work files.

Creating the EDTAMCB control block

The Assembler macro IEDTAMCB is used to generate the EDTAMCB control block.

Name	Operation	Operands
[name]	IEDTAMCB	[ {  D  | C } ] [,prefix] [,VERSION= {  1  | 2 } ]

name	– Symbolic name of the first DS statement when C is specified. – DSECT name if D is specified. If name is not specified then EDTAMCB is used (preceded by prefix if specified).
D C	A dummy section (DSECT) is generated. A memory section with symbolic addresses is generated (no CSECT statement).
prefix	One character with which the generated field names should start. If prefix is not specified, E is used by default.
VERSION	Selects which version of the control block is to be generated: Version 1 is used with the V16 format of the interface. Version 2 is used with the V17 format of the interface.

If the macro IEDTAMCB VERSION=2 is specified then the EDTAMCB control block is generated in the following form:

           IEDTAMCB D,VERSION=2
1 EDTAMCB  MFPRE DNAME=EDT,MF=D
2 EDTAMCB  DSECT ,
2                *,##### PREFIX=I, MACID= #####
1 *--------------- EDT UNIT NUMBER, EDTAMCB VERSION NUMBER --------------
1 EAMUNITC EQU   66                  EDT UNIT NUMBER
1 EAMVERSC EQU   2                   INTERFACE IDENTIFIER
1 *--------------- CONTROL BLOCK EDTAMCB --------------------------------
1 *                      *--- CONTROL BLOCK HEADER ----------------------
1 EAMFHE   DS    0XL8                GENERAL OPERAND LIST HEADER
1 EAMIFID  DS    0A                  INTERFACE IDENTIFIER
1 EAMUNIT  DC    AL2(XAMUNITC)       UNIT NUMBER
1          DS    AL1                 RESERVED
1 EAMVERS  DC    AL1(XAMVERSC)       FUNCTION INTERFACE VERSION NUMBER
1          DS    A                   RESERVED
1          DS    X                   RESERVED                       V17.0
1 *                      *---- FLAG-BYTE -------------------------- V16.4
1 EAMFLAG  DC    X'00'               FLAG                           V16.4
1 EAMIGN13 EQU   X'01'               IGNORE LINE MARK 13            V16.4
1 EAMNOMOD EQU   X'02'               INHIBIT SETTING MODIFIED FLAG  V16.6
1          DS    AL2                 RESERVED
1 *                      *--- INPUT PARAMETERS --------------------------
1 EAMFILE  DC    CL8' '              FILENAME
1 EAMDISP  DC    F'0'                DISPLACEMENT
1 EAMLKEY1 DC    H'8'                LENGTH OF KEY1
1 EAMLKEY2 DC    H'8'                LENGTH OF KEY2
1 *                      *--- INPUT PARAMETERS (ONLY IN MOVE MODE) ------
1 EAMPKEY  DC    H'8'                LENGTH OF KEY OUTPUT BUFFER
1 EAMPREC  DC    H'0'                LENGTH OF RECORD OUTPUTBUFFER
1 *                      *--- INPUT / OUTPUT PARAMETERS -----------------
1 EAMLKEY  DC    H'8'                LENGTH OF KEY
1 EAMLREC  DC    H'0'                LENGTH OF RECORD
1 EAMMARK  DS    0H                  LINE MARKS (16 BITS)
1 EAMMARK2 DC    X'00'               UPPER MARKS (8 BITS)
1 EAMMK15  EQU   X'80'               MARK 15 (BIT 2**15)
1 EAMMK14  EQU   X'40'               MARK 14 (BIT 2**14)
1 EAMMK13  EQU   X'20'               MARK 13 (BIT 2**13)
1 EAMMK09  EQU   X'02'               MARK 09 (BIT 2**09)
1 EAMMK08  EQU   X'01'               MARK 08 (BIT 2**08)
1 EAMMARK1 DC    X'00'               LOWER MARKS (8 BIT)
1 EAMMK07  EQU   X'80'               MARK 07 (BIT 2**07)
1 EAMMK06  EQU   X'40'               MARK 06 (BIT 2**06)
1 EAMMK05  EQU   X'20'               MARK 05 (BIT 2**05)
1 EAMMK04  EQU   X'10'               MARK 04 (BIT 2**04)
1 EAMMK03  EQU   X'08'               MARK 03 (BIT 2**03)
1 EAMMK02  EQU   X'04'               MARK 02 (BIT 2**02)
1 EAMMK01  EQU   X'02'               MARK 01 (BIT 2**01)
1          DS    AL2                 RESERVED
1 *--------------- LENGTH OF CONTROL BLOCK ------------------------------
1 EAMAMCBL EQU   *-EDTAMCB

Meaning of the control block fields		Length (bytes)	Format	Parameter type
				Call	Return
EAMUNIT	Unique identification of EDT.	2	X	C(M)
EAMVERS	Control block version number.	1	X	C(M)
EAMFLAG Flag EAMIGN13 Flag EAMNOMOD	The byte contains flags for record processing This flag must be set if records with mark 13 are to be read (IEDTGET) or are to be marked (IEDTPTM). This flag must be set if the work file is not to be marked as modified after a record has been written (IEDTPUT).	1		C C C
EAMFILE	The work file variable ($0..$22) specifying the work file (0-22) which is to be accessed, or the values G or L0 to L22 when the work file status is queried, or the value C when the copy buffer is deleted.	8	P	C
EAMDISP	This field contains: –the relative position of the required record when a record is read (IEDTGET) –the required search direction when a marked record is read (IEDTGTM).	4	X	C
EAMLKEY1	Length of the EDTKEY1 buffer	2	X	C
EAMLKEY2	Length of the EDTKEY2 buffer	2	X	C
EAMPKEY	The length of the output buffer for the line number must be entered in this field before a record is read (IEDTGET, IEDTGTM). Currently, only the value 8 is permitted.	2	X	C
EAMPREC	The length of the output buffer for the record must be entered in this field before a record is read (IEDTGET, IEDTGTM).	2	X	C
EAMLKEY	Length of the transferred data in the EDTKEY buffer. On a read operation, EDT passes the actual length of the read record number; on a write operation, the user passes the length of the record number to be written. Currently, only the value 8 is permitted.	2	X	C	R
EAMLREC	Length of the transferred data in the EDTREC buffer. On a read operation, EDT passes the actual length of the read record; on a write operation, the user passes the length of the record to be written.	2	X	C	R
EAMMARK	Specifies the marking of a record. It is used for both input and output. The mark field is used as additional information for each field. The user may use the marks 1..9 (EAMMK01..EAMMK09) as well as the marks 13, 14 and 15 EAMMK13, EAMMK14 and EAMMK15) in IEDTPUT and IEDTPTM as desired. The other marks are reserved for special functions.	2		C	R

C (M)	Call parameter	Must be supplied by the caller. This is set by the macro (when the P parameter is set) and should not be changed by the user.
R X P	Return parameter Binary format Printable	Supplied by EDT. Binary digits Printable texts (in the character set EDF03IRV).

Changes compared to the V16 format

• The EAMMMODB field and the two flags EAMMOVM and EAMLOCM are no longer used.

• The equates for the unused marks (EAMMK10, EAMMK11, EAMMK12 and EAMMK0) are no longer used.

Compatible V17 format

No restrictions.