setrlimit

setrlimit

Define UNIX System Services Resource Limits

Portability: UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
USAGE NOTES
RELATED FUNCTIONS

SYNOPSIS

#include <sys/resource.h>
int setrlimit(int resource,
              const struct rlimit *info);

DESCRIPTION

The setrlimit function defines resource limits for the calling process. Limits are expressed as a pair of integers, a soft limit and a hard limit. The soft limit controls the amount of the resource the program is actually allowed to consume, while the hard limit specifies an upper bound on the soft limit. The soft limit can be raised up to the hard limit value, but the hard limit can only be raised by a privileged (superuser) caller.

The resource argument defines the resource to which the limit applies. It should be specified as one of the symbolic values defined below.

RLIMIT_AS - Specifies the maximum size in bytes of the address space for this process. If the limit is exceeded, memory allocation functions such as malloc or GETMAIN will be unable to allocate additional memory.
Note: Setting this limit too low could cause the program to be terminated due to the inability of the library to obtain more stack space.
RLIMIT_CORE - Specifies the maximum size in bytes of an UNIX System Services memory dump (core file) for this process. A limit of 0 will prevent a dump file from being created.
RLIMIT_CPU - Specifies the maximum CPU time in seconds allowed for this address space. When the limit is exceeded, a SIGXCPU signal is sent to the process, and a small amount of additional time is allocated to allow a signal handler to execute.
RLIMIT_DATA - Specifies the maximum amount of memory available for data allocation using malloc or calloc . This limit is not enforced under UNIX System Services, and an attempt to set the limit lower than RLIM_INFINITY will be rejected.
RLIMIT_FSIZE - Specifies the maximum file size in bytes allowed for this process. A limit of 0 will prevent new files from being created. If an attempt is made to extend a file beyond the limit, a SIGXFSZ signal is sent to the process. The limit applies only to UNIX System Services HFS files, not to standard OS/390 data sets.
RLIMIT_NOFILE - The maximum number of file descriptors the process may have open. Any attempt to open a file with a file number above the limit will fail with errno set to EMFILE .
RLIMIT_STACK - The maximum amount of memory available for stack allocation. This limit is not enforced under UNIX System Services, and an attempt to set the limit lower than RLIM_INFINITY will be rejected.

The info argument is a pointer to a structure of type struct rlimit , which defines the soft and hard limits. The structure contains the following fields:

rlim_cur - the current (i.e., soft) limit
rlim_max - the maximum limit

RETURN VALUE

setrlimit returns 0 if successful, or -1 if unsuccessful.

USAGE NOTES

The setrlimit function can only be used with MVS 5.2.2 or a later release.

Note: Resource limits defined by setrlimit are propagated to child processes created by fork or exec . [cautionend]

RELATED FUNCTIONS

getrlimit

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