FREEE FREEE defines an element in the chain of elements that comprise the free element queue.
FREEQ in SVECTORS points to the chain of free elements, each of which is defined by the FREEE DSECT. 0 4
8
C
L
Hexadecillal Field
Displacement Name ------------ 0 FREENEXT DS " FREESPAR DS F FREEID DS FREENEXT FREESPAR
1F
CL11 1X , I I I , I I FREEID , Field Description, Contents, eeaning Address of next element in free queue
Spare field
Standard taskid displacement, which is: ID=X'OO'=> free element
252 lBe VM/310 Data Areas and Control Block Logic

GIVE/TAKE §lVE The format of a GIVE Request Table is: I 0 Synch Lock I , 4 Task name or A(GIVE Element) I I 8 A (GIVE Request Buffer) I I C A (GIVE Response Buffer) I .J When a task requests the services of another task via a GIVE request, the second field of
the table above contains the task name of the task to which the task is to be sent. When DMTGIV builds a GIVE element for the request, it overlays this task name with the address of the GIVE element.
The task Ferfor.ing the requested service builds a table called the TAKE request
table, which corresponds to the GIVE request table. GIVEE defines symbolic addresses for items used in processing a GIVE request. GIVEQ in SVECTORS points to the queue of GIVE elements used in task-to-task cOiimunicaticns. The GIVEADDR field of this DSECT is the address of a GIVE request table, which, in
turn, contains addresses of buffers for elements describing requests and resFonses to
requests. These tables are described below; the elements that fill the buffers are
described in "AFpendix C: RSCS Request Elements." 0 4
8
C
Hexadecimal Displacellent ------------ 0 4
8
C E F I , I GIVENEXT I I I I GIVEADDR I I I I GIVENAME I I I I/////////GIVESPAR/////////I GIVENID GIVERID I Field Name GIVENEXT DS 1F GIVEADDR DS 1F GIVENAME DS CL4 GIVESPAR DS AL2 GIVENID DS 1X GIVERID DS 1X Field Description, Contents, Meaning
Address of next GIVE element
Address of GIVE request table in sending task's storage
Task name of receiving task
Reserved for IBM use
1-byte identification of receiving task after
the TAKE request has been processed
1-byte identification of sending task Section 3. RSCS rata Areas and Contrcl Blocks 253