Request body and Length limit to share on Linkedin by API

POST	https://api.linkedin.com/v1/people/~/shares?format=json

Request body

		Field Description	Max Length (chars)
content		A collection of fields describing the shared content.
	title	The title of the content being shared.	200
	description	The description of the content being shared.	256
	submitted-url	A fully qualified URL for the content being shared.	n/a
	submitted-image-url	A fully qualified URL to a thumbnail image to accompany the shared content. The image should be at least 80 x 150px for best results.	n/a
comment		A comment by the member to associated with the share. If none of the above content parameters are provided, the comment must contain a URL to the content you want to share.  If the comment contains multiple URLs, only the first one will be analyzed for content to share.	700
visibility		A collection of visibility information about the share.
	code	One of the following values: anyone:  Share will be visible to all members. connections-only:  Share will only be visible to connections of the member performing the share.   This field is required in all sharing calls.	n/a

Share on Company page has the same max length limit as above.