WAIT — Wait for one or more events

The requirements for callers of WAIT are:

None.

When using LINKAGE=SVC (the default), the caller cannot have an EUT FRR established.

Before issuing the WAIT macro, the caller does not have to place any information into any register unless using it in register notation for a particular parameter, or using it as a base register.

Some callers depend on register contents remaining the same before and after issuing a service. If the system changes the contents of registers on which the caller depends, the caller must save them before issuing the service, and restore them after the system returns control.

None.

The WAIT macro is written as follows:

The parameters are explained as follows:

event nmbr,

Specifies the number of events waiting to occur.

ECB=ecb addr

ECBLIST=ecb list addr

Specifies the address of an ECB on a fullword boundary or the address of a virtual storage area containing one or more consecutive fullwords on a fullword boundary. Each fullword contains the address of an ECB; the high order bit in the last fullword must be set to one to indicate the end of the list.

The ECB parameter is valid only if the number of events is specified as one or is omitted. The number of ECBs in the list specified by the ECBLIST form must be equal to or greater than the specified number of events.

If you specify ECBLIST, ecb list addr and all ECBs on the list must be in the home address space.

,LONG=NO

,LONG=YES

Specifies whether the task is entering a long wait (YES) or a regular wait (NO).

,LINKAGE=SVC

,LINKAGE=SYSTEM

Specifies whether POST is to be called through an SVC (LINKAGE=SVC) or not (LINKAGE=SYSTEM).

When the caller is not in cross memory mode (the primary, secondary, and home address spaces are the same) and no EUT FRR is established, use LINKAGE=SVC. With this parameter, linkage is through an SVC instruction.

When the caller is in cross memory mode (the primary, secondary, and home address spaces are not the same) or if an EUT FRR is established, use LINKAGE=SYSTEM. With this parameter, linkage is through a PC instruction. Note that the ECB must be in the home address space.

,RELATED=value

Specifies information used to self-document macros by “relating” functions or services to corresponding functions or services. The format and contents of the information specified are at the discretion of the user and may be any valid coding values.

The RELATED parameter is available on macros that provide opposite services (for example, ATTACH/DETACH, GETMAIN/FREEMAIN, and LOAD/DELETE) and on macros that relate to previous occurrences of the same macros (for example, CHAP and ESTAE).

The RELATED parameter may be used, for example, as follows:

WAIT1   WAIT     1,ECB=ECB,RELATED=(RESUME1,
                 'WAIT FOR EVENT')
  .
  .
  .
RESUME1 POST     ECB,0,RELATED=(WAIT1,
                 'RESUME WAITER')

Note: Each of these macros will fit on one line when coded, so there is no need for a continuation indicator.

You have previously initiated one or more activities to be completed asynchronously to your processing. As each activity was initiated, you set up an ECB in which bits 0 and 1 were set to zero. You now wish to suspend your task via the WAIT macro until a specified number of these activities have been completed.

Completion of each activity must be made known to the system via the POST macro. POST causes an addressed ECB to be marked complete. If completion of the event satisfies the requirements of an outstanding WAIT, the waiting task is marked ready and will be executed when its priority allows.

These hexadecimal codes are described in z/OS MVS System Codes.

None.